diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index f79729cedd7..6b5dc4fe7fb 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -341,7 +341,7 @@ protected:
   bool GatherMedia(nsMediaList* aMedia,
                      bool aInAtRule);
   bool ParseMediaQuery(bool aInAtRule, nsMediaQuery **aQuery,
-                         bool *aParsedSomething, bool *aHitStop);
+                         bool *aHitStop);
   bool ParseMediaQueryExpression(nsMediaQuery* aQuery);
   void ProcessImport(const nsString& aURLSpec,
                      nsMediaList* aMedia,
@@ -1177,13 +1177,8 @@ CSSParserImpl::ParseMediaList(const nsSubstring& aBuffer,
   // to a media query.  (The main substative difference is the relative
   // precedence of commas and paretheses.)
 
-  if (!GatherMedia(aMediaList, PR_FALSE)) {
-    aMediaList->Clear();
-    aMediaList->SetNonEmpty(); // don't match anything
-    if (!mHTMLMediaMode) {
-      OUTPUT_ERROR();
-    }
-  }
+  GatherMedia(aMediaList, false); // can only fail on low-level error (OOM)
+
   nsresult rv = mScanner.GetLowLevelError();
   CLEAR_ERROR();
   ReleaseScanner();
@@ -1627,11 +1622,9 @@ CSSParserImpl::ParseURLOrString(nsString& aURL)
 bool
 CSSParserImpl::ParseMediaQuery(bool aInAtRule,
                                nsMediaQuery **aQuery,
-                               bool *aParsedSomething,
                                bool *aHitStop)
 {
   *aQuery = nsnull;
-  *aParsedSomething = PR_FALSE;
   *aHitStop = PR_FALSE;
 
   // "If the comma-separated list is the empty list it is assumed to
@@ -1656,9 +1649,8 @@ CSSParserImpl::ParseMediaQuery(bool aInAtRule,
   }
   UngetToken();
 
-  *aParsedSomething = PR_TRUE;
-
-  nsAutoPtr<nsMediaQuery> query(new nsMediaQuery);
+  nsMediaQuery* query = new nsMediaQuery;
+  *aQuery = query;
   if (!query) {
     mScanner.SetLowLevelError(NS_ERROR_OUT_OF_MEMORY);
     return PR_FALSE;
@@ -1735,7 +1727,6 @@ CSSParserImpl::ParseMediaQuery(bool aInAtRule,
       query->SetHadUnknownExpression();
     }
   }
-  *aQuery = query.forget();
   return PR_TRUE;
 }
 
@@ -1747,13 +1738,17 @@ CSSParserImpl::GatherMedia(nsMediaList* aMedia,
 {
   for (;;) {
     nsAutoPtr<nsMediaQuery> query;
-    bool parsedSomething, hitStop;
+    bool hitStop;
     if (!ParseMediaQuery(aInAtRule, getter_Transfers(query),
-                         &parsedSomething, &hitStop)) {
+                         &hitStop)) {
       NS_ASSERTION(!hitStop, "should return true when hit stop");
+      OUTPUT_ERROR();
       if (NS_FAILED(mScanner.GetLowLevelError())) {
         return PR_FALSE;
       }
+      if (query) {
+        query->SetHadUnknownExpression();
+      }
       if (aInAtRule) {
         const PRUnichar stopChars[] =
           { PRUnichar(','), PRUnichar('{'), PRUnichar(';'), PRUnichar(0) };
@@ -1768,9 +1763,6 @@ CSSParserImpl::GatherMedia(nsMediaList* aMedia,
         hitStop = PR_TRUE;
       }
     }
-    if (parsedSomething) {
-      aMedia->SetNonEmpty();
-    }
     if (query) {
       nsresult rv = aMedia->AppendQuery(query);
       if (NS_FAILED(rv)) {
diff --git a/layout/style/nsCSSStyleSheet.cpp b/layout/style/nsCSSStyleSheet.cpp
index cf6d6df3157..031f59d8212 100644
--- a/layout/style/nsCSSStyleSheet.cpp
+++ b/layout/style/nsCSSStyleSheet.cpp
@@ -542,8 +542,7 @@ NS_IMPL_RELEASE(nsMediaList)
 
 
 nsMediaList::nsMediaList()
-  : mIsEmpty(PR_TRUE)
-  , mStyleSheet(nsnull)
+  : mStyleSheet(nsnull)
 {
 }
 
@@ -556,10 +555,6 @@ nsMediaList::GetText(nsAString& aMediaText)
 {
   aMediaText.Truncate();
 
-  if (mArray.Length() == 0 && !mIsEmpty) {
-    aMediaText.AppendLiteral("not all");
-  }
-
   for (PRInt32 i = 0, i_end = mArray.Length(); i < i_end; ++i) {
     nsMediaQuery* query = mArray[i];
     NS_ENSURE_TRUE(query, NS_ERROR_FAILURE);
@@ -601,7 +596,7 @@ nsMediaList::Matches(nsPresContext* aPresContext,
       return PR_TRUE;
     }
   }
-  return mIsEmpty;
+  return mArray.IsEmpty();
 }
 
 nsresult
@@ -624,7 +619,6 @@ nsMediaList::Clone(nsMediaList** aResult)
       return NS_ERROR_OUT_OF_MEMORY;
     }
   }
-  result->mIsEmpty = mIsEmpty;
   NS_ADDREF(*aResult = result);
   return NS_OK;
 }
diff --git a/layout/style/nsIMediaList.h b/layout/style/nsIMediaList.h
index d07f076d2d4..7372c72725e 100644
--- a/layout/style/nsIMediaList.h
+++ b/layout/style/nsIMediaList.h
@@ -205,11 +205,7 @@ public:
 
   PRInt32 Count() { return mArray.Length(); }
   nsMediaQuery* MediumAt(PRInt32 aIndex) { return mArray[aIndex]; }
-  void Clear() { mArray.Clear(); mIsEmpty = PR_TRUE; }
-  // a media list with no items may not represent the lack of a media
-  // list; it could represent the empty string or something with parser
-  // errors, which means that the media list should never match
-  void SetNonEmpty() { mIsEmpty = PR_FALSE; }
+  void Clear() { mArray.Clear(); }
 
 protected:
   ~nsMediaList();
@@ -218,7 +214,6 @@ protected:
   nsresult Append(const nsAString & aOldMedium);
 
   nsTArray<nsAutoPtr<nsMediaQuery> > mArray;
-  bool mIsEmpty;
   // not refcounted; sheet will let us know when it goes away
   // mStyleSheet is the sheet that needs to be dirtied when this medialist
   // changes
diff --git a/layout/style/test/test_media_queries.html b/layout/style/test/test_media_queries.html
index a89a2555838..074e323d7d7 100644
--- a/layout/style/test/test_media_queries.html
+++ b/layout/style/test/test_media_queries.html
@@ -79,7 +79,7 @@ function run() {
     var sheet = parse_test_style_element.sheet; // XXX yikes, not live!
     if (sheet.cssRules.length == 1 &&
         sheet.cssRules[0].type == CSSRule.MEDIA_RULE)
-      return sheet.cssRules[0].media.mediaText != "screen";
+      return sheet.cssRules[0].media.mediaText != "screen, not all";
     ok(false, "unexpected result testing whether query " + q +
               " is parseable");
     return true; // doesn't matter, we already failed