diff --git a/content/base/public/nsContentCreatorFunctions.h b/content/base/public/nsContentCreatorFunctions.h
index a4c3f39a210..80ab4e80582 100644
--- a/content/base/public/nsContentCreatorFunctions.h
+++ b/content/base/public/nsContentCreatorFunctions.h
@@ -48,8 +48,8 @@ CreateHTMLElement(uint32_t aNodeType, already_AddRefed<nsINodeInfo> aNodeInfo,
                   mozilla::dom::FromParser aFromParser);
 
 nsresult
-NS_NewMathMLElement(nsIContent** aResult,
-                     already_AddRefed<nsINodeInfo> aNodeInfo);
+NS_NewMathMLElement(mozilla::dom::Element** aResult,
+                    already_AddRefed<nsINodeInfo> aNodeInfo);
 
 #ifdef MOZ_XUL
 nsresult
diff --git a/content/base/src/nsNameSpaceManager.cpp b/content/base/src/nsNameSpaceManager.cpp
index 9fd07e3e068..6a39a07b907 100644
--- a/content/base/src/nsNameSpaceManager.cpp
+++ b/content/base/src/nsNameSpaceManager.cpp
@@ -208,7 +208,10 @@ NS_NewElement(nsIContent** aResult,
   }
 #endif
   if (ns == kNameSpaceID_MathML) {
-    return NS_NewMathMLElement(aResult, aNodeInfo);
+    nsCOMPtr<Element> el;
+    nsresult rv = NS_NewMathMLElement(getter_AddRefs(el), aNodeInfo);
+    el.forget(aResult);
+    return rv;
   }
   if (ns == kNameSpaceID_SVG) {
     return NS_NewSVGElement(aResult, aNodeInfo, aFromParser);
diff --git a/content/mathml/content/src/nsMathMLElementFactory.cpp b/content/mathml/content/src/nsMathMLElementFactory.cpp
index 44249689af9..d8e5ff37b6f 100644
--- a/content/mathml/content/src/nsMathMLElementFactory.cpp
+++ b/content/mathml/content/src/nsMathMLElementFactory.cpp
@@ -7,9 +7,11 @@
 #include "nsGkAtoms.h"
 #include "nsMathMLElement.h"
 
+using namespace mozilla::dom;
+
 // MathML Element Factory (declared in nsContentCreatorFunctions.h)
 nsresult
-NS_NewMathMLElement(nsIContent** aResult, already_AddRefed<nsINodeInfo> aNodeInfo)
+NS_NewMathMLElement(Element** aResult, already_AddRefed<nsINodeInfo> aNodeInfo)
 {
   aNodeInfo.get()->SetIDAttributeAtom(nsGkAtoms::id);