--- a/gfx/thebes/gfxFontconfigUtils.cpp
+++ b/gfx/thebes/gfxFontconfigUtils.cpp
@@ -259,18 +259,18 @@ gfxFontconfigUtils::NewPattern(const nsT
             // aliases (so that the preferred font depends on language).
             // However, this would give them lower priority than subsequent
             // non-generic families in the list.  To ensure that subsequent
             // families do not have a higher priority, they are given weak
             // bindings.
             for (PRUint32 g = 0;
                  g < NS_ARRAY_LENGTH(sFontconfigGenerics);
                  ++g) {
-                if (FcStrCmpIgnoreCase(ToFcChar8(sFontconfigGenerics[g]),
-                                       ToFcChar8(family.get()))) {
+                if (0 == FcStrCmpIgnoreCase(ToFcChar8(sFontconfigGenerics[g]),
+                                            ToFcChar8(family.get()))) {
                     useWeakBinding = PR_TRUE;
                     break;
                 }
             }
         } else {
             AddWeakString(pattern, FC_FAMILY, family.get());
         }
     }