--- a/dom/html/nsGenericHTMLElement.cpp
+++ b/dom/html/nsGenericHTMLElement.cpp
@@ -1734,27 +1734,27 @@ nsGenericHTMLElement::GetURIListAttr(nsI
 
   nsString::const_iterator end;
   value.EndReading(end);
 
   nsAString::const_iterator iter;
   value.BeginReading(iter);
 
   while (iter != end) {
-    while (nsCRT::IsAsciiSpace(*iter) && iter != end) {
+    while (*iter == ' ' && iter != end) {
       ++iter;
     }
 
     if (iter == end) {
       break;
     }
 
     nsAString::const_iterator start = iter;
 
-    while (iter != end && !nsCRT::IsAsciiSpace(*iter)) {
+    while (iter != end && *iter != ' ') {
       ++iter;
     }
 
     if (!aResult.IsEmpty()) {
       aResult.Append(NS_LITERAL_STRING(" "));
     }
 
     const nsSubstring& uriPart = Substring(start, iter);