diff --git a/gfx/thebes/gfxPlatformFontList.cpp b/gfx/thebes/gfxPlatformFontList.cpp
index a463210537d4..d7c9fa4a027e 100644
--- a/gfx/thebes/gfxPlatformFontList.cpp
+++ b/gfx/thebes/gfxPlatformFontList.cpp
@@ -281,7 +281,7 @@ gfxPlatformFontList::LoadBadUnderlineList()
     for (PRUint32 i = 0; i < numFonts; i++) {
         nsAutoString key;
         GenerateFontListKey(blacklist[i], key);
-        mBadUnderlineFamilyNames.Put(key);
+        mBadUnderlineFamilyNames.PutEntry(key);
     }
 }
 
diff --git a/gfx/thebes/gfxPlatformFontList.h b/gfx/thebes/gfxPlatformFontList.h
index 6893189f7367..412a311877bb 100644
--- a/gfx/thebes/gfxPlatformFontList.h
+++ b/gfx/thebes/gfxPlatformFontList.h
@@ -40,7 +40,7 @@
 
 #include "nsDataHashtable.h"
 #include "nsRefPtrHashtable.h"
-#include "nsHashSets.h"
+#include "nsTHashtable.h"
 
 #include "gfxFontUtils.h"
 #include "gfxFont.h"
@@ -214,7 +214,7 @@ protected:
     // on pages with lots of problems
     nsString mReplacementCharFallbackFamily;
 
-    nsStringHashSet mBadUnderlineFamilyNames;
+    nsTHashtable<nsStringHashKey> mBadUnderlineFamilyNames;
 
     // data used as part of the font cmap loading process
     nsTArray<nsRefPtr<gfxFontFamily> > mFontFamiliesToLoad;