diff --git a/mozilla/gfx/src/gtk/nsFontMetricsGTK.cpp b/mozilla/gfx/src/gtk/nsFontMetricsGTK.cpp
index 0dbdf8f3926..ec177650798 100644
--- a/mozilla/gfx/src/gtk/nsFontMetricsGTK.cpp
+++ b/mozilla/gfx/src/gtk/nsFontMetricsGTK.cpp
@@ -2223,7 +2223,8 @@ GetFontNames(char* aPattern)
       continue;
     }
 
-    nsAutoString familyName2(NS_ConvertASCIItoUCS2(familyName));
+    nsAutoString familyName2;
+    familyName2.AssignWithConversion(familyName);
     family =
       (nsFontFamily*) PL_HashTableLookup(gFamilies, (nsString*) &familyName2);
     if (!family) {