diff --git a/mozilla/editor/libeditor/html/nsHTMLCSSUtils.cpp b/mozilla/editor/libeditor/html/nsHTMLCSSUtils.cpp
index 516faf86ec0..d8ad6abfe2d 100644
--- a/mozilla/editor/libeditor/html/nsHTMLCSSUtils.cpp
+++ b/mozilla/editor/libeditor/html/nsHTMLCSSUtils.cpp
@@ -1059,6 +1059,7 @@ nsHTMLCSSUtils::GetCSSEquivalentToHTMLInlineStyleSet(nsIDOMNode * aNode,
   nsresult res = GetElementContainerOrSelf(aNode, getter_AddRefs(theElement));
   if (NS_FAILED(res)) return res;
   nsCOMPtr<nsIDOMNode> theNode = do_QueryInterface(theElement);
+  aValueString.Truncate();
 
   if (theElement && IsCSSEditableProperty(theNode, aHTMLProperty, aAttribute)) {
     // Yes, the requested HTML style has a CSS equivalence in this implementation
diff --git a/mozilla/editor/libeditor/html/nsHTMLEditorStyle.cpp b/mozilla/editor/libeditor/html/nsHTMLEditorStyle.cpp
index d6cd0712c58..20e3da80825 100644
--- a/mozilla/editor/libeditor/html/nsHTMLEditorStyle.cpp
+++ b/mozilla/editor/libeditor/html/nsHTMLEditorStyle.cpp
@@ -1119,7 +1119,7 @@ nsHTMLEditor::GetInlinePropertyBase(nsIAtom *aProperty,
                 mHTMLCSSUtils->IsCSSEditableProperty(node, aProperty, aAttribute)) {
               // the HTML styles defined by aProperty/aAttribute has a CSS equivalence
               // in this implementation for node; let's check if it carries those css styles
-              if (aValue) firstValue.Assign(*aValue);
+              if (aValue) theValue.Assign(*aValue);
               mHTMLCSSUtils->IsCSSEquivalentToHTMLInlineStyleSet(node, aProperty, aAttribute,
                                                                  isSet, theValue,
                                                                  COMPUTED_STYLE_TYPE);