diff --git a/mozilla/extensions/transformiix/source/xpath/AttributeExpr.cpp b/mozilla/extensions/transformiix/source/xpath/AttributeExpr.cpp
index 1bb513b9667..509c251037c 100644
--- a/mozilla/extensions/transformiix/source/xpath/AttributeExpr.cpp
+++ b/mozilla/extensions/transformiix/source/xpath/AttributeExpr.cpp
@@ -128,14 +128,16 @@ MBool AttributeExpr::matches(Node* node, Node* context, ContextState* cs) {
         Node* parent = cs->getParentNode(node);
         if (parent) XMLDOMUtils::getNameSpace(prefixForNode, (Element*)parent, nsForNode);
         String nsForTest;
-        cs->getNameSpaceURIFromPrefix(this->prefix,nsForTest);
+        if (prefix.length())
+            cs->getNameSpaceURIFromPrefix(prefix, nsForTest);
         if (!nsForTest.isEqual(nsForNode)) return MB_FALSE;
         return localName.isEqual(this->name);
     }
     else {
         if (isNamespaceWild) return nodeName.isEqual(this->name);
         String nsForTest;
-        cs->getNameSpaceURIFromPrefix(this->prefix, nsForTest);
+        if (prefix.length())
+            cs->getNameSpaceURIFromPrefix(prefix, nsForTest);
         if (nsForTest.length() > 0) return MB_FALSE;
         return nodeName.isEqual(this->name);
     }
diff --git a/mozilla/extensions/transformiix/source/xpath/ElementExpr.cpp b/mozilla/extensions/transformiix/source/xpath/ElementExpr.cpp
index 0f9d54f2b8d..4994b631909 100644
--- a/mozilla/extensions/transformiix/source/xpath/ElementExpr.cpp
+++ b/mozilla/extensions/transformiix/source/xpath/ElementExpr.cpp
@@ -111,7 +111,8 @@ MBool ElementExpr::matches(Node* node, Node* context, ContextState* cs) {
         //-- compare namespaces
         String nsURI;
         // use context to get namespace for testing against
-        cs->getNameSpaceURIFromPrefix(this->prefix, nsURI);
+        if (prefix.length())
+            cs->getNameSpaceURIFromPrefix(prefix, nsURI);
 
         String nsURI2;
         String prefix2;