diff --git a/config/autoconf.mk.in b/config/autoconf.mk.in
index aeb424357f0..5402059b7bd 100644
--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -253,7 +253,6 @@ MOZ_TREE_CAIRO = @MOZ_TREE_CAIRO@
 MOZ_TREE_PIXMAN = @MOZ_TREE_PIXMAN@
 
 MOZ_UPDATE_XTERM = @MOZ_UPDATE_XTERM@
-MOZ_MATHML = @MOZ_MATHML@
 MOZ_CSS_ANIMATIONS = @MOZ_CSS_ANIMATIONS@
 MOZ_PERMISSIONS = @MOZ_PERMISSIONS@
 MOZ_XTF = @MOZ_XTF@
diff --git a/configure.in b/configure.in
index 299f6058f86..13c988dd068 100644
--- a/configure.in
+++ b/configure.in
@@ -4802,7 +4802,6 @@ MOZ_OFFICIAL_BRANDING=
 MOZ_FEEDS=1
 MOZ_INSTALLER=1
 MOZ_JSDEBUGGER=1
-MOZ_MATHML=1
 MOZ_CSS_ANIMATIONS=1
 MOZ_MORK=
 MOZ_MORKREADER=1
@@ -6408,17 +6407,6 @@ for extension in $MOZ_EXTENSIONS; do
     fi
 done
 
-dnl ========================================================
-dnl MathML on by default
-dnl ========================================================
-MOZ_ARG_DISABLE_BOOL(mathml,
-[  --disable-mathml        Disable MathML support],
-    MOZ_MATHML=,
-    MOZ_MATHML=1 )
-if test "$MOZ_MATHML"; then
-  AC_DEFINE(MOZ_MATHML)
-fi
-
 AC_DEFINE(MOZ_CSS_ANIMATIONS)
 
 dnl ========================================================
@@ -8749,7 +8737,6 @@ AC_SUBST(MOZ_UPDATE_XTERM)
 AC_SUBST(MINIMO)
 AC_SUBST(MOZ_PLATFORM_MAEMO)
 AC_SUBST(MOZ_AUTH_EXTENSION)
-AC_SUBST(MOZ_MATHML)
 AC_SUBST(MOZ_CSS_ANIMATIONS)
 AC_SUBST(MOZ_PERMISSIONS)
 AC_SUBST(MOZ_XTF)
diff --git a/content/Makefile.in b/content/Makefile.in
index aaa02552aa6..f57abdcf4bc 100644
--- a/content/Makefile.in
+++ b/content/Makefile.in
@@ -43,7 +43,7 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= content
-PARALLEL_DIRS		= base canvas events html smil svg xml xul xbl xslt
+PARALLEL_DIRS		= base canvas events html mathml smil svg xml xul xbl xslt
 
 ifdef MOZ_MEDIA
 PARALLEL_DIRS	+= media
@@ -53,10 +53,6 @@ ifdef MOZ_XTF
 PARALLEL_DIRS   += xtf
 endif
 
-ifdef MOZ_MATHML
-PARALLEL_DIRS   += mathml
-endif
-
 ifdef ENABLE_TESTS
 TOOL_DIRS += test
 endif
diff --git a/content/base/public/nsContentCreatorFunctions.h b/content/base/public/nsContentCreatorFunctions.h
index e55273e6fdd..f31e9baeed2 100644
--- a/content/base/public/nsContentCreatorFunctions.h
+++ b/content/base/public/nsContentCreatorFunctions.h
@@ -111,11 +111,9 @@ already_AddRefed<nsGenericHTMLElement>
 CreateHTMLElement(PRUint32 aNodeType, already_AddRefed<nsINodeInfo> aNodeInfo,
                   mozilla::dom::FromParser aFromParser);
 
-#ifdef MOZ_MATHML
 nsresult
 NS_NewMathMLElement(nsIContent** aResult,
                      already_AddRefed<nsINodeInfo> aNodeInfo);
-#endif
 
 #ifdef MOZ_XUL
 nsresult
diff --git a/content/base/src/nsGkAtomList.h b/content/base/src/nsGkAtomList.h
index ed3769ea08f..212a3037a9d 100644
--- a/content/base/src/nsGkAtomList.h
+++ b/content/base/src/nsGkAtomList.h
@@ -1383,7 +1383,6 @@ GK_ATOM(to, "to")
 GK_ATOM(XML, "XML")
 #endif
 
-#ifdef MOZ_MATHML
 // internal MathML attributes: different from columnalign_, columnlines_,
 // fontstyle_, rowalign_ and rowlines_
 GK_ATOM(_moz_math_columnalign_, "_moz-math-columnalign")
@@ -1667,7 +1666,6 @@ GK_ATOM(veryverythinmathspace_, "veryverythinmathspace")
 GK_ATOM(voffset_, "voffset")
 GK_ATOM(xref_, "xref")
 GK_ATOM(math, "math") // the only one without an underscore
-#endif
 
 #ifndef DISABLE_XFORMS_HOOKS
 GK_ATOM(avg, "avg")
diff --git a/content/base/src/nsNameSpaceManager.cpp b/content/base/src/nsNameSpaceManager.cpp
index 6cbeedc6741..349c5b3bd86 100644
--- a/content/base/src/nsNameSpaceManager.cpp
+++ b/content/base/src/nsNameSpaceManager.cpp
@@ -235,11 +235,9 @@ NS_NewElement(nsIContent** aResult, PRInt32 aElementType,
     return NS_NewXULElement(aResult, aNodeInfo);
   }
 #endif
-#ifdef MOZ_MATHML
   if (aElementType == kNameSpaceID_MathML) {
     return NS_NewMathMLElement(aResult, aNodeInfo);
   }
-#endif
   if (aElementType == kNameSpaceID_SVG) {
     return NS_NewSVGElement(aResult, aNodeInfo, aFromParser);
   }
@@ -265,9 +263,7 @@ NameSpaceManagerImpl::HasElementCreator(PRInt32 aNameSpaceID)
 #ifdef MOZ_XUL
          aNameSpaceID == kNameSpaceID_XUL ||
 #endif
-#ifdef MOZ_MATHML
          aNameSpaceID == kNameSpaceID_MathML ||
-#endif
          aNameSpaceID == kNameSpaceID_SVG ||
          aNameSpaceID == kNameSpaceID_XMLEvents ||
          PR_FALSE;
diff --git a/content/events/public/nsEventStates.h b/content/events/public/nsEventStates.h
index 5f041016c30..bcca9891579 100644
--- a/content/events/public/nsEventStates.h
+++ b/content/events/public/nsEventStates.h
@@ -242,9 +242,7 @@ private:
 #define NS_EVENT_STATE_LOADING       NS_DEFINE_EVENT_STATE_MACRO(22)
 // Content is of a type that gecko can't handle.
 #define NS_EVENT_STATE_TYPE_UNSUPPORTED NS_DEFINE_EVENT_STATE_MACRO(23)
-#ifdef MOZ_MATHML
 #define NS_EVENT_STATE_INCREMENT_SCRIPT_LEVEL NS_DEFINE_EVENT_STATE_MACRO(24)
-#endif
 // Handler for the content has been blocked.
 #define NS_EVENT_STATE_HANDLER_BLOCKED NS_DEFINE_EVENT_STATE_MACRO(25)
 // Handler for the content has been disabled.
diff --git a/content/svg/content/src/nsSVGFeatures.cpp b/content/svg/content/src/nsSVGFeatures.cpp
index d36adb261a1..63269debf89 100644
--- a/content/svg/content/src/nsSVGFeatures.cpp
+++ b/content/svg/content/src/nsSVGFeatures.cpp
@@ -106,9 +106,7 @@ nsSVGFeatures::HaveExtension(const nsAString& aExtension)
 {
 #define SVG_SUPPORTED_EXTENSION(str) if (aExtension.EqualsLiteral(str)) return PR_TRUE;
   SVG_SUPPORTED_EXTENSION("http://www.w3.org/1999/xhtml")
-#ifdef MOZ_MATHML
   SVG_SUPPORTED_EXTENSION("http://www.w3.org/1998/Math/MathML")
-#endif
 #undef SVG_SUPPORTED_EXTENSION
 
   return PR_FALSE;
diff --git a/content/xml/document/src/nsXMLContentSink.cpp b/content/xml/document/src/nsXMLContentSink.cpp
index 2b5c99ef64e..71c0e08205d 100644
--- a/content/xml/document/src/nsXMLContentSink.cpp
+++ b/content/xml/document/src/nsXMLContentSink.cpp
@@ -1657,10 +1657,8 @@ nsXMLContentSink::IsMonolithicContainer(nsINodeInfo* aNodeInfo)
           (aNodeInfo->NameAtom() == nsGkAtoms::tr ||
            aNodeInfo->NameAtom() == nsGkAtoms::select ||
            aNodeInfo->NameAtom() == nsGkAtoms::object ||
-           aNodeInfo->NameAtom() == nsGkAtoms::applet))
-#ifdef MOZ_MATHML
-       || (aNodeInfo->NamespaceID() == kNameSpaceID_MathML &&
+           aNodeInfo->NameAtom() == nsGkAtoms::applet)) ||
+          (aNodeInfo->NamespaceID() == kNameSpaceID_MathML &&
           (aNodeInfo->NameAtom() == nsGkAtoms::math))
-#endif
           );
 }
diff --git a/dom/base/nsDOMClassInfo.cpp b/dom/base/nsDOMClassInfo.cpp
index 37e58718825..c2159ab1ef8 100644
--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -1423,10 +1423,8 @@ static nsDOMClassInfoData sClassInfoData[] = {
 
   NS_DEFINE_CLASSINFO_DATA(MozTouchEvent, nsDOMGenericSH,
                            DOM_DEFAULT_SCRIPTABLE_FLAGS)
-#ifdef MOZ_MATHML
   NS_DEFINE_CLASSINFO_DATA_WITH_NAME(MathMLElement, Element, nsElementSH,
                                      ELEMENT_SCRIPTABLE_FLAGS)
-#endif
 
   NS_DEFINE_CLASSINFO_DATA(Worker, nsDOMGenericSH,
                            DOM_DEFAULT_SCRIPTABLE_FLAGS)
@@ -4139,7 +4137,6 @@ nsDOMClassInfo::Init()
     DOM_CLASSINFO_UI_EVENT_MAP_ENTRIES
   DOM_CLASSINFO_MAP_END
 
-#ifdef MOZ_MATHML
   DOM_CLASSINFO_MAP_BEGIN_NO_CLASS_IF(MathMLElement, nsIDOMElement)
     DOM_CLASSINFO_MAP_ENTRY(nsIDOMElement)
     DOM_CLASSINFO_MAP_ENTRY(nsIDOMNSElement)
@@ -4148,7 +4145,6 @@ nsDOMClassInfo::Init()
     DOM_CLASSINFO_MAP_ENTRY(nsIDOM3Node)
     DOM_CLASSINFO_MAP_ENTRY(nsIDOMNodeSelector)
   DOM_CLASSINFO_MAP_END
-#endif
 
   DOM_CLASSINFO_MAP_BEGIN(Worker, nsIWorker)
     DOM_CLASSINFO_MAP_ENTRY(nsIWorker)
diff --git a/dom/base/nsDOMClassInfoClasses.h b/dom/base/nsDOMClassInfoClasses.h
index 4ab501c1178..0614baaf8a6 100644
--- a/dom/base/nsDOMClassInfoClasses.h
+++ b/dom/base/nsDOMClassInfoClasses.h
@@ -455,9 +455,7 @@ DOMCI_CLASS(SimpleGestureEvent)
 
 DOMCI_CLASS(MozTouchEvent)
 
-#ifdef MOZ_MATHML
 DOMCI_CLASS(MathMLElement)
-#endif
 
 DOMCI_CLASS(Worker)
 DOMCI_CLASS(ChromeWorker)
diff --git a/gfx/src/nsBoundingMetrics.h b/gfx/src/nsBoundingMetrics.h
index fb733d4a027..6a9bf029e07 100644
--- a/gfx/src/nsBoundingMetrics.h
+++ b/gfx/src/nsBoundingMetrics.h
@@ -46,7 +46,6 @@
  * but not the rest of nsFontMetrics, or vice versa.
  */
 
-#ifdef MOZ_MATHML
 struct nsBoundingMetrics {
 
     ///////////
@@ -115,6 +114,5 @@ struct nsBoundingMetrics {
         width += bm.width;
     }
 };
-#endif // MOZ_MATHML
 
 #endif // __nsBoundingMetrics_h
diff --git a/gfx/src/nsFontMetrics.cpp b/gfx/src/nsFontMetrics.cpp
index bdc7d3a5942..d4c45405b89 100644
--- a/gfx/src/nsFontMetrics.cpp
+++ b/gfx/src/nsFontMetrics.cpp
@@ -348,7 +348,6 @@ nsFontMetrics::DrawString(const PRUnichar* aString, PRUint32 aLength,
     textRun->Draw(aContext->ThebesContext(), pt, 0, aLength, &provider, nsnull);
 }
 
-#ifdef MOZ_MATHML
 nsBoundingMetrics
 nsFontMetrics::GetBoundingMetrics(const PRUnichar *aString, PRUint32 aLength,
                                   nsRenderingContext *aContext)
@@ -371,4 +370,3 @@ nsFontMetrics::GetBoundingMetrics(const PRUnichar *aString, PRUint32 aLength,
     m.width        = NSToCoordRound( theMetrics.mAdvanceWidth);
     return m;
 }
-#endif /* MOZ_MATHML */
diff --git a/gfx/src/nsFontMetrics.h b/gfx/src/nsFontMetrics.h
index bd270074278..889de9b56d4 100644
--- a/gfx/src/nsFontMetrics.h
+++ b/gfx/src/nsFontMetrics.h
@@ -217,11 +217,9 @@ public:
                     nsRenderingContext *aContext,
                     nsRenderingContext *aTextRunConstructionContext);
 
-#ifdef MOZ_MATHML
     nsBoundingMetrics GetBoundingMetrics(const PRUnichar *aString,
                                          PRUint32 aLength,
                                          nsRenderingContext *aContext);
-#endif /* MOZ_MATHML */
 
     void SetTextRunRTL(PRBool aIsRTL) { mTextRunRTL = aIsRTL; }
     PRBool GetTextRunRTL() { return mTextRunRTL; }
diff --git a/gfx/src/nsRenderingContext.cpp b/gfx/src/nsRenderingContext.cpp
index c6e26ab2093..924cbd324c9 100644
--- a/gfx/src/nsRenderingContext.cpp
+++ b/gfx/src/nsRenderingContext.cpp
@@ -540,7 +540,6 @@ nsRenderingContext::GetWidth(const PRUnichar *aString, PRUint32 aLength)
     return width;
 }
 
-#ifdef MOZ_MATHML
 nsBoundingMetrics
 nsRenderingContext::GetBoundingMetrics(const PRUnichar* aString,
                                        PRUint32 aLength)
@@ -565,7 +564,6 @@ nsRenderingContext::GetBoundingMetrics(const PRUnichar* aString,
     }
     return totalMetrics;
 }
-#endif
 
 void
 nsRenderingContext::DrawString(const char *aString, PRUint32 aLength,
diff --git a/gfx/src/nsRenderingContext.h b/gfx/src/nsRenderingContext.h
index ac700a04bb9..f8d4e975c70 100644
--- a/gfx/src/nsRenderingContext.h
+++ b/gfx/src/nsRenderingContext.h
@@ -132,10 +132,8 @@ public:
     nscoord GetWidth(const char* aString, PRUint32 aLength);
     nscoord GetWidth(const PRUnichar *aString, PRUint32 aLength);
 
-#ifdef MOZ_MATHML
     nsBoundingMetrics GetBoundingMetrics(const PRUnichar *aString,
                                          PRUint32 aLength);
-#endif
 
     void DrawString(const nsString& aString, nscoord aX, nscoord aY);
     void DrawString(const char *aString, PRUint32 aLength,
diff --git a/intl/unicharutil/tables/Makefile.in b/intl/unicharutil/tables/Makefile.in
index 1465be50cdf..458d47e1b51 100644
--- a/intl/unicharutil/tables/Makefile.in
+++ b/intl/unicharutil/tables/Makefile.in
@@ -50,12 +50,9 @@ _PROP_TABLES = \
 	html40Symbols.properties \
 	html40Special.properties \
 	transliterate.properties \
+	mathml20.properties \
 	$(NULL)
 
-ifdef MOZ_MATHML
-_PROP_TABLES += mathml20.properties
-endif
-
 ifeq ($(MOZ_WIDGET_TOOLKIT), qt)
 CFLAGS          += $(MOZ_QT_CFLAGS)
 CXXFLAGS        += $(MOZ_QT_CFLAGS)
diff --git a/layout/Makefile.in b/layout/Makefile.in
index 263298d1eb1..312ddb16394 100644
--- a/layout/Makefile.in
+++ b/layout/Makefile.in
@@ -54,18 +54,13 @@ PARALLEL_DIRS = \
 		xul/base/public \
 		xul/base/src \
 		ipc \
+		mathml \
 		$(NULL)
 
 ifdef NS_PRINTING
 PARALLEL_DIRS += printing
 endif
 
-ifdef MOZ_MATHML
-PARALLEL_DIRS += \
-  mathml \
-  $(NULL)
-endif
-
 PARALLEL_DIRS += inspector/public inspector/src
 ifdef ENABLE_TESTS
 PARALLEL_DIRS += inspector/tests
diff --git a/layout/base/Makefile.in b/layout/base/Makefile.in
index 991df4fbb80..935006100c8 100644
--- a/layout/base/Makefile.in
+++ b/layout/base/Makefile.in
@@ -166,13 +166,9 @@ LOCAL_INCLUDES += \
 		-I$(srcdir)/../../content/html/content/src \
 		-I$(srcdir)/../../content/svg/content/src \
 		-I$(srcdir)/../svg/base/src \
+		-I$(srcdir)/../mathml \
 		$(NULL)
 
-ifdef MOZ_MATHML
-LOCAL_INCLUDES += \
-        -I$(srcdir)/../mathml
-endif
-
 CXXFLAGS += $(MOZ_CAIRO_CFLAGS)
 
 DEFINES += -D_IMPL_NS_LAYOUT
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index beb427e6a31..e34dbd8f0b2 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -139,9 +139,7 @@
 
 #undef NOISY_FIRST_LETTER
 
-#ifdef MOZ_MATHML
 #include "nsMathMLParts.h"
-#endif
 #include "nsSVGFeatures.h"
 #include "nsSVGEffects.h"
 #include "nsSVGUtils.h"
@@ -1903,11 +1901,9 @@ nsCSSFrameConstructor::ConstructTable(nsFrameConstructorState& aState,
 
   // Create the outer table frame which holds the caption and inner table frame
   nsIFrame* newFrame;
-#ifdef MOZ_MATHML
   if (kNameSpaceID_MathML == nameSpaceID)
     newFrame = NS_NewMathMLmtableOuterFrame(mPresShell, outerStyleContext);
   else
-#endif
     newFrame = NS_NewTableOuterFrame(mPresShell, outerStyleContext);
 
   nsIFrame* geometricParent =
@@ -1919,11 +1915,9 @@ nsCSSFrameConstructor::ConstructTable(nsFrameConstructorState& aState,
 
   // Create the inner table frame
   nsIFrame* innerFrame;
-#ifdef MOZ_MATHML
   if (kNameSpaceID_MathML == nameSpaceID)
     innerFrame = NS_NewMathMLmtableFrame(mPresShell, styleContext);
   else
-#endif
     innerFrame = NS_NewTableFrame(mPresShell, styleContext);
  
   InitAndRestoreFrame(aState, content, newFrame, nsnull, innerFrame);
@@ -1984,11 +1978,9 @@ nsCSSFrameConstructor::ConstructTableRow(nsFrameConstructorState& aState,
   const PRUint32 nameSpaceID = aItem.mNameSpaceID;
 
   nsIFrame* newFrame;
-#ifdef MOZ_MATHML
   if (kNameSpaceID_MathML == nameSpaceID)
     newFrame = NS_NewMathMLmtrFrame(mPresShell, styleContext);
   else
-#endif
     newFrame = NS_NewTableRowFrame(mPresShell, styleContext);
 
   if (NS_UNLIKELY(!newFrame)) {
@@ -2072,7 +2064,6 @@ nsCSSFrameConstructor::ConstructTableCell(nsFrameConstructorState& aState,
 
   PRBool borderCollapse = IsBorderCollapse(aParentFrame);
   nsIFrame* newFrame;
-#ifdef MOZ_MATHML
   // <mtable> is border separate in mathml.css and the MathML code doesn't implement
   // border collapse. For those users who style <mtable> with border collapse,
   // give them the default non-MathML table frames that understand border collapse.
@@ -2083,7 +2074,6 @@ nsCSSFrameConstructor::ConstructTableCell(nsFrameConstructorState& aState,
   if (kNameSpaceID_MathML == nameSpaceID && !borderCollapse)
     newFrame = NS_NewMathMLmtdFrame(mPresShell, styleContext);
   else
-#endif
     // Warning: If you change this and add a wrapper frame around table cell
     // frames, make sure Bug 368554 doesn't regress!
     // See IsInAutoWidthTableCellForQuirk() in nsImageFrame.cpp.    
@@ -2104,14 +2094,10 @@ nsCSSFrameConstructor::ConstructTableCell(nsFrameConstructorState& aState,
   // Create a block frame that will format the cell's content
   PRBool isBlock;
   nsIFrame* cellInnerFrame;
-#ifdef MOZ_MATHML
   if (kNameSpaceID_MathML == nameSpaceID) {
     cellInnerFrame = NS_NewMathMLmtdInnerFrame(mPresShell, innerPseudoStyle);
     isBlock = PR_FALSE;
-  }
-  else
-#endif
-  {
+  } else {
     cellInnerFrame = NS_NewBlockFormattingContext(mPresShell, innerPseudoStyle);
     isBlock = PR_TRUE;
   }
@@ -3674,9 +3660,7 @@ nsCSSFrameConstructor::ConstructFrameFromItemInternal(FrameConstructionItem& aIt
   NS_ASSERTION(!(bits & _bit1) || !(bits & _bit2),     \
                "Only one of these bits should be set")
   CHECK_ONLY_ONE_BIT(FCDATA_FUNC_IS_FULL_CTOR, FCDATA_FORCE_NULL_ABSPOS_CONTAINER);
-#ifdef MOZ_MATHML
   CHECK_ONLY_ONE_BIT(FCDATA_FUNC_IS_FULL_CTOR, FCDATA_WRAP_KIDS_IN_BLOCKS);
-#endif
   CHECK_ONLY_ONE_BIT(FCDATA_FUNC_IS_FULL_CTOR, FCDATA_MAY_NEED_SCROLLFRAME);
   CHECK_ONLY_ONE_BIT(FCDATA_FUNC_IS_FULL_CTOR, FCDATA_IS_POPUP);
   CHECK_ONLY_ONE_BIT(FCDATA_FUNC_IS_FULL_CTOR, FCDATA_SKIP_ABSPOS_PUSH);
@@ -3810,7 +3794,6 @@ nsCSSFrameConstructor::ConstructFrameFromItemInternal(FrameConstructionItem& aIt
     }
 #endif
 
-#ifdef MOZ_MATHML
     if (NS_SUCCEEDED(rv) && (bits & FCDATA_WRAP_KIDS_IN_BLOCKS)) {
       nsFrameItems newItems;
       nsFrameItems currentBlock;
@@ -3839,7 +3822,6 @@ nsCSSFrameConstructor::ConstructFrameFromItemInternal(FrameConstructionItem& aIt
 
       childItems = newItems;
     }
-#endif
 
     // Set the frame's initial child list
     // Note that MathML depends on this being called even if
@@ -4587,7 +4569,6 @@ nsCSSFrameConstructor::ResolveStyleContext(nsStyleContext* aParentStyleContext,
 }
 
 // MathML Mod - RBS
-#ifdef MOZ_MATHML
 nsresult
 nsCSSFrameConstructor::FlushAccumulatedBlock(nsFrameConstructorState& aState,
                                              nsIContent* aContent,
@@ -4702,7 +4683,6 @@ nsCSSFrameConstructor::FindMathMLData(Element* aElement,
   return FindDataByTag(aTag, aElement, aStyleContext, sMathMLData,
                        NS_ARRAY_LENGTH(sMathMLData));
 }
-#endif // MOZ_MATHML
 
 // Only outer <svg> elements can be floated or positioned.  All other SVG
 // should be in-flow.
@@ -5182,11 +5162,9 @@ nsCSSFrameConstructor::AddFrameConstructionItemsInternal(nsFrameConstructorState
     if (!data) {
       data = FindXULTagData(element, aTag, aNameSpaceID, styleContext);
     }
-#ifdef MOZ_MATHML
     if (!data) {
       data = FindMathMLData(element, aTag, aNameSpaceID, styleContext);
     }
-#endif
     if (!data) {
       data = FindSVGData(element, aTag, aNameSpaceID, aParentFrame,
                          styleContext);
@@ -6546,14 +6524,12 @@ nsCSSFrameConstructor::ContentAppended(nsIContent*     aContainer,
     return NS_OK;
   }
   
-#ifdef MOZ_MATHML
   if (parentFrame->IsFrameOfType(nsIFrame::eMathML)) {
     LAYOUT_PHASE_TEMP_EXIT();
     nsresult rv = RecreateFramesForContent(parentFrame->GetContent(), PR_FALSE);
     LAYOUT_PHASE_TEMP_REENTER();
     return rv;
   }
-#endif
 
   // If the frame we are manipulating is a ``special'' frame (that is, one
   // that's been created as a result of a block-in-inline situation) then we
@@ -7013,14 +6989,12 @@ nsCSSFrameConstructor::ContentRangeInserted(nsIContent*            aContainer,
     return NS_OK;
   }
 
-#ifdef MOZ_MATHML
   if (parentFrame->IsFrameOfType(nsIFrame::eMathML)) {
     LAYOUT_PHASE_TEMP_EXIT();
     nsresult rv = RecreateFramesForContent(parentFrame->GetContent(), PR_FALSE);
     LAYOUT_PHASE_TEMP_REENTER();
     return rv;
   }
-#endif
 
   nsFrameConstructorState state(mPresShell, mFixedContainingBlock,
                                 GetAbsoluteContainingBlock(parentFrame),
@@ -7438,7 +7412,6 @@ nsCSSFrameConstructor::ContentRemoved(nsIContent* aContainer,
       return rv;
     }
 
-#ifdef MOZ_MATHML
     // If we're a child of MathML, then we should reframe the MathML content.
     // If we're non-MathML, then we would be wrapped in a block so we need to
     // check our grandparent in that case.
@@ -7451,7 +7424,6 @@ nsCSSFrameConstructor::ContentRemoved(nsIContent* aContainer,
       LAYOUT_PHASE_TEMP_REENTER();
       return rv;
     }
-#endif
 
     // Undo XUL wrapping if it's no longer needed.
     // (If we're in the XUL block-wrapping situation, parentFrame is the
diff --git a/layout/base/nsCSSFrameConstructor.h b/layout/base/nsCSSFrameConstructor.h
index d68317534c2..c16c7e86de5 100644
--- a/layout/base/nsCSSFrameConstructor.h
+++ b/layout/base/nsCSSFrameConstructor.h
@@ -678,12 +678,10 @@ private:
      frame.  If this is not set, the frame will be pushed as the
      absolute containing block as needed, based on its style */
 #define FCDATA_FORCE_NULL_ABSPOS_CONTAINER 0x10
-#ifdef MOZ_MATHML
   /* If FCDATA_WRAP_KIDS_IN_BLOCKS is set, the inline kids of the frame
      will be wrapped in blocks.  This is only usable for MathML at the
      moment. */
 #define FCDATA_WRAP_KIDS_IN_BLOCKS 0x20
-#endif /* MOZ_MATHML */
   /* If FCDATA_SUPPRESS_FRAME is set, no frame should be created for the
      content.  If this bit is set, nothing else in the struct needs to be
      set. */
@@ -1271,7 +1269,6 @@ private:
                                nsTArray<nsIAnonymousContentCreator::ContentInfo>& aAnonContent);
 
 //MathML Mod - RBS
-#ifdef MOZ_MATHML
   /**
    * Takes the frames in aBlockItems and wraps them in a new anonymous block
    * frame whose content is aContent and whose parent will be aParentFrame.
@@ -1289,7 +1286,6 @@ private:
                                                      nsIAtom* aTag,
                                                      PRInt32 aNameSpaceID,
                                                      nsStyleContext* aStyleContext);
-#endif
 
   // Function to find FrameConstructionData for aContent.  Will return
   // null if aContent is not XUL.
diff --git a/layout/base/nsDisplayItemTypes.h b/layout/base/nsDisplayItemTypes.h
index b9ec6ebbcbc..cd934864261 100644
--- a/layout/base/nsDisplayItemTypes.h
+++ b/layout/base/nsDisplayItemTypes.h
@@ -119,7 +119,6 @@ enum Type {
 #endif
 #endif
 
-#ifdef MOZ_MATHML
   TYPE_MATHML_BAR,
   TYPE_MATHML_CHAR_BACKGROUND,
   TYPE_MATHML_CHAR_FOREGROUND,
@@ -131,7 +130,6 @@ enum Type {
   TYPE_MATHML_BOUNDING_METRICS,
   TYPE_MATHML_CHAR_DEBUG,
 #endif
-#endif
 
 #ifdef NS_DEBUG
   TYPE_DEBUG_BORDER,
diff --git a/layout/build/Makefile.in b/layout/build/Makefile.in
index 6979a4ec5e3..753e1fec493 100644
--- a/layout/build/Makefile.in
+++ b/layout/build/Makefile.in
@@ -81,6 +81,7 @@ SHARED_LIBRARY_LIBS = \
 	../style/$(LIB_PREFIX)gkstyle_s.$(LIB_SUFFIX) \
 	../tables/$(LIB_PREFIX)gktable_s.$(LIB_SUFFIX) \
 	../xul/base/src/$(LIB_PREFIX)gkxulbase_s.$(LIB_SUFFIX) \
+	../mathml/$(LIB_PREFIX)gkmathml_s.$(LIB_SUFFIX) \
 	$(DEPTH)/content/base/src/$(LIB_PREFIX)gkconbase_s.$(LIB_SUFFIX) \
 	$(DEPTH)/content/canvas/src/$(LIB_PREFIX)gkconcvs_s.$(LIB_SUFFIX) \
 	$(DEPTH)/content/events/src/$(LIB_PREFIX)gkconevents_s.$(LIB_SUFFIX) \
@@ -112,6 +113,7 @@ SHARED_LIBRARY_LIBS = \
 	$(DEPTH)/caps/src/$(LIB_PREFIX)caps_s.$(LIB_SUFFIX) \
 	$(DEPTH)/editor/libeditor/html/$(LIB_PREFIX)htmleditor_s.$(LIB_SUFFIX) \
 	$(DEPTH)/editor/txtsvc/src/$(LIB_PREFIX)txtsvc_s.$(LIB_SUFFIX) \
+	$(DEPTH)/content/mathml/content/src/$(LIB_PREFIX)gkcontentmathml_s.$(LIB_SUFFIX) \
 	$(NULL)
 
 ifneq (,$(filter qt gtk2,$(MOZ_WIDGET_TOOLKIT)))
@@ -220,13 +222,6 @@ LOCAL_INCLUDES  += \
       $(NULL)
 SHARED_LIBRARY_LIBS += ../inspector/src/$(LIB_PREFIX)inspector_s.$(LIB_SUFFIX)
 
-ifdef MOZ_MATHML
-SHARED_LIBRARY_LIBS += \
-		../mathml/$(LIB_PREFIX)gkmathml_s.$(LIB_SUFFIX) \
-		$(DEPTH)/content/mathml/content/src/$(LIB_PREFIX)gkcontentmathml_s.$(LIB_SUFFIX) \
-		$(NULL)
-endif
-
 ifdef MOZ_XTF
 SHARED_LIBRARY_LIBS += \
 		$(DEPTH)/content/xtf/src/$(LIB_PREFIX)gkcontentxtf_s.$(LIB_SUFFIX) \
@@ -300,6 +295,7 @@ LOCAL_INCLUDES	+= -I$(srcdir)/../base \
 		   -I$(srcdir)/../style \
 		   -I$(srcdir)/../xul/content/src \
 		   -I$(srcdir)/../xul/base/src \
+		   -I$(srcdir)/../mathml \
 		   -I$(topsrcdir)/content/base/src \
  		   -I$(topsrcdir)/content/canvas/src \
 		   -I$(topsrcdir)/content/html/content/src \
@@ -335,10 +331,6 @@ LOCAL_INCLUDES	+= -I$(srcdir)/../base \
 		   -I$(topsrcdir)/content/svg/content/src \
 		   $(NULL)
 
-ifdef MOZ_MATHML
-LOCAL_INCLUDES	+= -I$(srcdir)/../mathml
-endif
-
 DEFINES += -D_IMPL_NS_LAYOUT
 
 ifeq ($(OS_ARCH),IRIX)
diff --git a/layout/build/nsContentDLF.cpp b/layout/build/nsContentDLF.cpp
index d0623a9035d..7d8897ba640 100644
--- a/layout/build/nsContentDLF.cpp
+++ b/layout/build/nsContentDLF.cpp
@@ -105,9 +105,7 @@ static const char* const gHTMLTypes[] = {
 static const char* const gXMLTypes[] = {
   TEXT_XML,
   APPLICATION_XML,
-#ifdef MOZ_MATHML
   APPLICATION_MATHML_XML,
-#endif
   APPLICATION_RDF_XML,
   TEXT_RDF,
   0
diff --git a/layout/build/nsContentDLF.h b/layout/build/nsContentDLF.h
index a93a5062b3e..87463f68b41 100644
--- a/layout/build/nsContentDLF.h
+++ b/layout/build/nsContentDLF.h
@@ -90,13 +90,6 @@ private:
 nsresult
 NS_NewContentDocumentLoaderFactory(nsIDocumentLoaderFactory** aResult);
 
-#ifdef MOZ_MATHML
-#define CONTENTDLF_MATHML_CATEGORIES \
-    { "Gecko-Content-Viewers", APPLICATION_MATHML_XML, "@mozilla.org/content/document-loader-factory;1" },
-#else
-#define CONTENTDLF_MATHML_CATEGORIES
-#endif
-
 #ifdef MOZ_WEBM
 #define CONTENTDLF_WEBM_CATEGORIES \
     { "Gecko-Content-Viewers", VIDEO_WEBM, "@mozilla.org/content/document-loader-factory;1" }, \
@@ -123,7 +116,7 @@ NS_NewContentDocumentLoaderFactory(nsIDocumentLoaderFactory** aResult);
     { "Gecko-Content-Viewers", APPLICATION_CACHED_XUL, "@mozilla.org/content/document-loader-factory;1" }, \
     { "Gecko-Content-Viewers", VIEWSOURCE_CONTENT_TYPE, "@mozilla.org/content/document-loader-factory;1" }, \
     { "Gecko-Content-Viewers", IMAGE_SVG_XML, "@mozilla.org/content/document-loader-factory;1" }, \
-    CONTENTDLF_MATHML_CATEGORIES \
+    { "Gecko-Content-Viewers", APPLICATION_MATHML_XML, "@mozilla.org/content/document-loader-factory;1" }, \
     CONTENTDLF_WEBM_CATEGORIES
 
 #endif
diff --git a/layout/build/nsLayoutStatics.cpp b/layout/build/nsLayoutStatics.cpp
index e378385de8a..bd0db506041 100644
--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -89,6 +89,8 @@
 #include "nsListControlFrame.h"
 #include "nsHTMLInputElement.h"
 #include "nsSVGUtils.h"
+#include "nsMathMLAtoms.h"
+#include "nsMathMLOperators.h"
 
 #ifdef MOZ_XUL
 #include "nsXULPopupManager.h"
@@ -100,11 +102,6 @@
 #include "inDOMView.h"
 #endif
 
-#ifdef MOZ_MATHML
-#include "nsMathMLAtoms.h"
-#include "nsMathMLOperators.h"
-#endif
-
 #include "nsHTMLEditor.h"
 #include "nsTextServicesDocument.h"
 
@@ -215,9 +212,7 @@ nsLayoutStatics::Initialize()
 
 #endif
 
-#ifdef MOZ_MATHML
   nsMathMLOperators::AddRefTable();
-#endif
 
   nsEditProperty::RegisterAtoms();
   nsTextServicesDocument::RegisterAtoms();
@@ -328,9 +323,7 @@ nsLayoutStatics::Shutdown()
   nsSprocketLayout::Shutdown();
 #endif
 
-#ifdef MOZ_MATHML
   nsMathMLOperators::ReleaseTable();
-#endif
 
   nsCSSFrameConstructor::ReleaseGlobals();
   nsFloatManager::Shutdown();
diff --git a/layout/generic/nsHTMLReflowMetrics.h b/layout/generic/nsHTMLReflowMetrics.h
index e0a0da5f9ab..9a8734f6bb6 100644
--- a/layout/generic/nsHTMLReflowMetrics.h
+++ b/layout/generic/nsHTMLReflowMetrics.h
@@ -44,14 +44,12 @@
 #include "nsISupports.h"
 #include "nsMargin.h"
 #include "nsRect.h"
-#include "nsBoundingMetrics.h" // for MOZ_MATHML
+#include "nsBoundingMetrics.h"
 
 //----------------------------------------------------------------------
 
 // Option flags
-#ifdef MOZ_MATHML
 #define NS_REFLOW_CALC_BOUNDING_METRICS  0x0001
-#endif
 
 /**
  * When we store overflow areas as an array of scrollable and visual
@@ -238,7 +236,6 @@ struct nsHTMLReflowMetrics {
 
   enum { ASK_FOR_BASELINE = nscoord_MAX };
 
-#ifdef MOZ_MATHML
   // Metrics that _exactly_ enclose the text to allow precise MathML placements.
   // If the NS_REFLOW_CALC_BOUNDING_METRICS flag is set, then the caller is 
   // requesting that you also compute additional details about your inner
@@ -246,7 +243,6 @@ struct nsHTMLReflowMetrics {
   // msup is the smallest rectangle that _exactly_ encloses both the text
   // of the base and the text of the superscript.
   nsBoundingMetrics mBoundingMetrics;  // [OUT]
-#endif
 
   // Carried out bottom margin values. This is the collapsed
   // (generational) bottom margin value.
diff --git a/layout/generic/nsTextFrameThebes.cpp b/layout/generic/nsTextFrameThebes.cpp
index e8baf8f0b84..778dfb7e1f6 100644
--- a/layout/generic/nsTextFrameThebes.cpp
+++ b/layout/generic/nsTextFrameThebes.cpp
@@ -6809,10 +6809,8 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
   gfxFont::BoundingBoxType boundingBoxType = IsFloatingFirstLetterChild() ?
                                                gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS :
                                                gfxFont::LOOSE_INK_EXTENTS;
-#ifdef MOZ_MATHML
   NS_ASSERTION(!(NS_REFLOW_CALC_BOUNDING_METRICS & aMetrics.mFlags),
                "We shouldn't be passed NS_REFLOW_CALC_BOUNDING_METRICS anymore");
-#endif
 
   PRInt32 limitLength = length;
   PRInt32 forceBreak = aLineLayout.GetForcedBreakPosition(mContent);
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 342b65ad2d3..01fbc806cd6 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -5620,13 +5620,11 @@ CSSParserImpl::ParseSingleValueProperty(nsCSSValue& aValue,
     return PR_FALSE;
   }
 
-#ifdef MOZ_MATHML
   // We only allow 'script-level' when unsafe rules are enabled, because
   // otherwise it could interfere with rulenode optimizations if used in
   // a non-MathML-enabled document.
   if (aPropID == eCSSProperty_script_level && !mUnsafeRulesEnabled)
     return PR_FALSE;
-#endif
 
   const PRInt32 *kwtable = nsCSSProps::kKeywordTableTable[aPropID];
   switch (nsCSSProps::ValueRestrictions(aPropID)) {
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 75be71b565e..68d6f742d1d 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -2514,7 +2514,6 @@ CSS_PROP_XUL(
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 
-#ifdef MOZ_MATHML
 #ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
 CSS_PROP_FONT(
     -moz-script-level,
@@ -2551,7 +2550,6 @@ CSS_PROP_FONT(
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 #endif
-#endif
 
 CSS_PROP_SVGRESET(
     clip-path,
diff --git a/layout/style/nsCSSPseudoClassList.h b/layout/style/nsCSSPseudoClassList.h
index bc6c7d53af6..5904c837382 100644
--- a/layout/style/nsCSSPseudoClassList.h
+++ b/layout/style/nsCSSPseudoClassList.h
@@ -159,11 +159,9 @@ CSS_STATE_PSEUDO_CLASS(mozHandlerBlocked, ":-moz-handler-blocked",
 CSS_STATE_PSEUDO_CLASS(mozHandlerCrashed, ":-moz-handler-crashed",
                        NS_EVENT_STATE_HANDLER_CRASHED)
 
-#ifdef MOZ_MATHML
 CSS_STATE_PSEUDO_CLASS(mozMathIncrementScriptLevel,
                        ":-moz-math-increment-script-level",
                        NS_EVENT_STATE_INCREMENT_SCRIPT_LEVEL)
-#endif
 
 // CSS 3 UI
 // http://www.w3.org/TR/2004/CR-css3-ui-20040511/#pseudo-classes
diff --git a/layout/style/nsCSSPseudoElementList.h b/layout/style/nsCSSPseudoElementList.h
index bd2b5b45b8c..bf622459aec 100644
--- a/layout/style/nsCSSPseudoElementList.h
+++ b/layout/style/nsCSSPseudoElementList.h
@@ -81,10 +81,8 @@ CSS_PSEUDO_ELEMENT(mozFocusOuter, ":-moz-focus-outer", 0)
 CSS_PSEUDO_ELEMENT(mozListBullet, ":-moz-list-bullet", 0)
 CSS_PSEUDO_ELEMENT(mozListNumber, ":-moz-list-number", 0)
 
-#ifdef MOZ_MATHML
 CSS_PSEUDO_ELEMENT(mozMathStretchy, ":-moz-math-stretchy", 0)
 CSS_PSEUDO_ELEMENT(mozMathAnonymous, ":-moz-math-anonymous", 0)
-#endif
 
 // HTML5 Forms pseudo elements
 CSS_PSEUDO_ELEMENT(mozProgressBar, ":-moz-progress-bar", 0)
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 9e951f17a4a..ba99a43c260 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -1373,9 +1373,7 @@ CheckFontCallback(const nsRuleData* aRuleData,
       (size.GetUnit() == eCSSUnit_Enumerated &&
        (size.GetIntValue() == NS_STYLE_FONT_SIZE_SMALLER ||
         size.GetIntValue() == NS_STYLE_FONT_SIZE_LARGER)) ||
-#ifdef MOZ_MATHML
       aRuleData->ValueForScriptLevel()->GetUnit() == eCSSUnit_Integer ||
-#endif
       (weight.GetUnit() == eCSSUnit_Enumerated &&
        (weight.GetIntValue() == NS_STYLE_FONT_WEIGHT_BOLDER ||
         weight.GetIntValue() == NS_STYLE_FONT_WEIGHT_LIGHTER))) {
@@ -1595,7 +1593,7 @@ static const CheckCallbackFn gCheckCallbacks[] = {
 
 };
 
-#if defined(MOZ_MATHML) && defined(DEBUG)
+#ifdef DEBUG
 static PRBool
 AreAllMathMLPropertiesUndefined(const nsRuleData* aRuleData)
 {
@@ -1631,12 +1629,10 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
          aSID, total, specified, inherited);
 #endif
 
-#ifdef MOZ_MATHML
   NS_ASSERTION(aSID != eStyleStruct_Font ||
                mPresContext->Document()->GetMathMLEnabled() ||
                AreAllMathMLPropertiesUndefined(aRuleData),
                "MathML style property was defined even though MathML is disabled");
-#endif
 
   /*
    * Return the most specific information we can: prefer None or Full
@@ -1647,7 +1643,6 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
   if (inherited == total)
     result = eRuleFullInherited;
   else if (specified == total
-#ifdef MOZ_MATHML
            // MathML defines 3 properties in Font that will never be set when
            // MathML is not in use. Therefore if all but three
            // properties have been set, and MathML is not enabled, we can treat
@@ -1656,7 +1651,6 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
            // (see nsMathMLElement::BindToTree).
            || (aSID == eStyleStruct_Font && specified + 3 == total &&
                !mPresContext->Document()->GetMathMLEnabled())
-#endif
           ) {
     if (inherited == 0)
       result = eRuleFullReset;
@@ -2382,7 +2376,6 @@ nsRuleNode::AdjustLogicalBoxProp(nsStyleContext* aContext,
                                                                               \
   return data_;
 
-#ifdef MOZ_MATHML
 // This function figures out how much scaling should be suppressed to
 // satisfy scriptminsize. This is our attempt to implement
 // http://www.w3.org/TR/MathML2/chapter3.html#id.3.3.4.2.2
@@ -2441,7 +2434,6 @@ ComputeScriptLevelSize(const nsStyleFont* aFont, const nsStyleFont* aParentFont,
     return NS_MIN(scriptLevelSize, NS_MAX(*aUnconstrainedSize, minScriptSize));
   }
 }
-#endif
 
 struct SetFontSizeCalcOps : public css::BasicCoordCalcOps,
                             public css::NumbersAlreadyNormalizedOps
@@ -2592,7 +2584,6 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
   } else {
     NS_ASSERTION(eCSSUnit_Null == sizeValue->GetUnit(),
                  "What kind of font-size value is this?");
-#ifdef MOZ_MATHML
     // if aUsedStartStruct is true, then every single property in the
     // font struct is being set all at once. This means scriptlevel is not
     // going to have any influence on the font size; there is no need to
@@ -2604,7 +2595,6 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
       aCanStoreInRuleTree = PR_FALSE;
       *aSize = aScriptLevelAdjustedParentSize;
     }
-#endif
   }
 
   // We want to zoom the cascaded size so that em-based measurements,
@@ -2811,7 +2801,6 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
               defaultVariableFont->stretch,
               0, 0, 0, systemFont.stretch);
 
-#ifdef MOZ_MATHML
   // Compute scriptlevel, scriptminsize and scriptsizemultiplier now so
   // they're available for font-size computation.
 
@@ -2851,7 +2840,6 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
   else if (eCSSUnit_Initial == scriptLevelValue->GetUnit()) {
     aFont->mScriptLevel = 0;
   }
-#endif
 
   // font-feature-settings
   const nsCSSValue* featureSettingsValue =
@@ -2885,18 +2873,15 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
 
   // font-size: enum, length, percent, inherit
   nscoord scriptLevelAdjustedParentSize = aParentFont->mSize;
-#ifdef MOZ_MATHML
   nscoord scriptLevelAdjustedUnconstrainedParentSize;
   scriptLevelAdjustedParentSize =
     ComputeScriptLevelSize(aFont, aParentFont, aPresContext,
                            &scriptLevelAdjustedUnconstrainedParentSize);
   NS_ASSERTION(!aUsedStartStruct || aFont->mScriptUnconstrainedSize == aFont->mSize,
                "If we have a start struct, we should have reset everything coming in here");
-#endif
   SetFontSize(aPresContext, aRuleData, aFont, aParentFont, &aFont->mSize,
               systemFont, aParentFont->mSize, scriptLevelAdjustedParentSize,
               aUsedStartStruct, atRoot, aCanStoreInRuleTree);
-#ifdef MOZ_MATHML
   if (aParentFont->mSize == aParentFont->mScriptUnconstrainedSize &&
       scriptLevelAdjustedParentSize == scriptLevelAdjustedUnconstrainedParentSize) {
     // Fast path: we have not been affected by scriptminsize so we don't
@@ -2914,7 +2899,6 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
   }
   NS_ASSERTION(aFont->mScriptUnconstrainedSize <= aFont->mSize,
                "scriptminsize should never be making things bigger");
-#endif
 
   // enforce the user' specified minimum font-size on the value that we expose
   // (but don't change font-size:0)
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index b71c6b214ac..6bf3e84183f 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -121,25 +121,21 @@ nsStyleFont::nsStyleFont(const nsFont& aFont, nsPresContext *aPresContext)
 {
   MOZ_COUNT_CTOR(nsStyleFont);
   mSize = mFont.size = nsStyleFont::ZoomText(aPresContext, mFont.size);
-#ifdef MOZ_MATHML
   mScriptUnconstrainedSize = mSize;
   mScriptMinSize = aPresContext->CSSTwipsToAppUnits(
       NS_POINTS_TO_TWIPS(NS_MATHML_DEFAULT_SCRIPT_MIN_SIZE_PT));
   mScriptLevel = 0;
   mScriptSizeMultiplier = NS_MATHML_DEFAULT_SCRIPT_SIZE_MULTIPLIER;
-#endif
 }
 
 nsStyleFont::nsStyleFont(const nsStyleFont& aSrc)
   : mFont(aSrc.mFont)
   , mSize(aSrc.mSize)
   , mGenericID(aSrc.mGenericID)
-#ifdef MOZ_MATHML
   , mScriptLevel(aSrc.mScriptLevel)
   , mScriptUnconstrainedSize(aSrc.mScriptUnconstrainedSize)
   , mScriptMinSize(aSrc.mScriptMinSize)
   , mScriptSizeMultiplier(aSrc.mScriptSizeMultiplier)
-#endif
 {
   MOZ_COUNT_CTOR(nsStyleFont);
 }
@@ -150,13 +146,11 @@ nsStyleFont::nsStyleFont(nsPresContext* aPresContext)
 {
   MOZ_COUNT_CTOR(nsStyleFont);
   mSize = mFont.size = nsStyleFont::ZoomText(aPresContext, mFont.size);
-#ifdef MOZ_MATHML
   mScriptUnconstrainedSize = mSize;
   mScriptMinSize = aPresContext->CSSTwipsToAppUnits(
       NS_POINTS_TO_TWIPS(NS_MATHML_DEFAULT_SCRIPT_MIN_SIZE_PT));
   mScriptLevel = 0;
   mScriptSizeMultiplier = NS_MATHML_DEFAULT_SCRIPT_SIZE_MULTIPLIER;
-#endif
 }
 
 void* 
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 0957b8d08d9..e2eab26b081 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -138,14 +138,12 @@ struct nsStyleFont {
   PRUint8 mGenericID;   // [inherited] generic CSS font family, if any;
                         // value is a kGenericFont_* constant, see nsFont.h.
 
-#ifdef MOZ_MATHML
   // MathML scriptlevel support
   PRInt8  mScriptLevel;          // [inherited]
   // The value mSize would have had if scriptminsize had never been applied
   nscoord mScriptUnconstrainedSize;
   nscoord mScriptMinSize;        // [inherited] length
   float   mScriptSizeMultiplier; // [inherited]
-#endif
 };
 
 struct nsStyleGradientStop {
diff --git a/parser/htmlparser/src/CParserContext.cpp b/parser/htmlparser/src/CParserContext.cpp
index 82e54b83f8a..5f67abdf9db 100644
--- a/parser/htmlparser/src/CParserContext.cpp
+++ b/parser/htmlparser/src/CParserContext.cpp
@@ -88,9 +88,7 @@ CParserContext::SetMimeType(const nsACString& aMimeType)
            mMimeType.EqualsLiteral(APPLICATION_XHTML_XML) ||
            mMimeType.EqualsLiteral(TEXT_XUL)              ||
            mMimeType.EqualsLiteral(IMAGE_SVG_XML)         ||
-#ifdef MOZ_MATHML
            mMimeType.EqualsLiteral(APPLICATION_MATHML_XML) ||
-#endif
            mMimeType.EqualsLiteral(APPLICATION_RDF_XML)   ||
            mMimeType.EqualsLiteral(TEXT_RDF))
     mDocType = eXML;
diff --git a/toolkit/toolkit-makefiles.sh b/toolkit/toolkit-makefiles.sh
index 2ae4f436705..6d9c1f82646 100644
--- a/toolkit/toolkit-makefiles.sh
+++ b/toolkit/toolkit-makefiles.sh
@@ -364,6 +364,13 @@ MAKEFILES_libnestegg="
   media/libnestegg/src/Makefile
 "
 
+MAKEFILES_mathml="
+  content/mathml/Makefile
+  content/mathml/content/Makefile
+  content/mathml/content/src/Makefile
+  layout/mathml/Makefile
+"
+
 MAKEFILES_netwerk="
   netwerk/Makefile
   netwerk/base/Makefile
@@ -752,6 +759,7 @@ add_makefiles "
   $MAKEFILES_libjar
   $MAKEFILES_libreg
   $MAKEFILES_libpref
+  $MAKEFILES_mathml
   $MAKEFILES_plugin
   $MAKEFILES_netwerk
   $MAKEFILES_uriloader
@@ -1102,15 +1110,6 @@ if [ "$MOZ_MAPINFO" ]; then
   "
 fi
 
-if [ "$MOZ_MATHML" ]; then
-  add_makefiles "
-    content/mathml/Makefile
-    content/mathml/content/Makefile
-    content/mathml/content/src/Makefile
-    layout/mathml/Makefile
-  "
-fi
-
 if [ "$MOZ_SMIL" ]; then
   add_makefiles "
     content/smil/Makefile