diff --git a/mozilla/content/html/style/src/nsCSSStyleSheet.cpp b/mozilla/content/html/style/src/nsCSSStyleSheet.cpp
index 6d25d50daf2..d1ce83b139f 100644
--- a/mozilla/content/html/style/src/nsCSSStyleSheet.cpp
+++ b/mozilla/content/html/style/src/nsCSSStyleSheet.cpp
@@ -3663,16 +3663,19 @@ static PRBool SelectorMatches(RuleProcessorData &data,
     } else {
       result = localTrue;
       nsAttrSelector* attr = aSelector->mAttrList;
-      nsAutoString value;
       do {
-        nsresult  attrState = data.mContent->GetAttr(attr->mNameSpace, attr->mAttr, value);
-        if (NS_FAILED(attrState) || (NS_CONTENT_ATTR_NOT_THERE == attrState)) {
+        if (!data.mContent->HasAttr(attr->mNameSpace, attr->mAttr)) {
           result = localFalse;
         }
-        else {
+        else if (attr->mFunction != NS_ATTR_FUNC_SET) {
+          nsAutoString value;
+          nsresult attrState =
+              data.mContent->GetAttr(attr->mNameSpace, attr->mAttr, value);
+          NS_ASSERTION(NS_SUCCEEDED(attrState) &&
+                       NS_CONTENT_ATTR_NOT_THERE != attrState,
+                       "HasAttr lied or GetAttr failed");
           PRBool isCaseSensitive = attr->mCaseSensitive;
           switch (attr->mFunction) {
-            case NS_ATTR_FUNC_SET:    break;
             case NS_ATTR_FUNC_EQUALS: 
               if (isCaseSensitive) {
                 result = PRBool(localTrue == value.Equals(attr->mValue));
diff --git a/mozilla/layout/style/nsCSSStyleSheet.cpp b/mozilla/layout/style/nsCSSStyleSheet.cpp
index 6d25d50daf2..d1ce83b139f 100644
--- a/mozilla/layout/style/nsCSSStyleSheet.cpp
+++ b/mozilla/layout/style/nsCSSStyleSheet.cpp
@@ -3663,16 +3663,19 @@ static PRBool SelectorMatches(RuleProcessorData &data,
     } else {
       result = localTrue;
       nsAttrSelector* attr = aSelector->mAttrList;
-      nsAutoString value;
       do {
-        nsresult  attrState = data.mContent->GetAttr(attr->mNameSpace, attr->mAttr, value);
-        if (NS_FAILED(attrState) || (NS_CONTENT_ATTR_NOT_THERE == attrState)) {
+        if (!data.mContent->HasAttr(attr->mNameSpace, attr->mAttr)) {
           result = localFalse;
         }
-        else {
+        else if (attr->mFunction != NS_ATTR_FUNC_SET) {
+          nsAutoString value;
+          nsresult attrState =
+              data.mContent->GetAttr(attr->mNameSpace, attr->mAttr, value);
+          NS_ASSERTION(NS_SUCCEEDED(attrState) &&
+                       NS_CONTENT_ATTR_NOT_THERE != attrState,
+                       "HasAttr lied or GetAttr failed");
           PRBool isCaseSensitive = attr->mCaseSensitive;
           switch (attr->mFunction) {
-            case NS_ATTR_FUNC_SET:    break;
             case NS_ATTR_FUNC_EQUALS: 
               if (isCaseSensitive) {
                 result = PRBool(localTrue == value.Equals(attr->mValue));