diff --git a/mozilla/gfx/src/gtk/nsRenderingContextGTK.cpp b/mozilla/gfx/src/gtk/nsRenderingContextGTK.cpp
index 4e7714bc84a..5651ea4ecff 100644
--- a/mozilla/gfx/src/gtk/nsRenderingContextGTK.cpp
+++ b/mozilla/gfx/src/gtk/nsRenderingContextGTK.cpp
@@ -903,7 +903,7 @@ nsRenderingContextGTK::DrawString(const char *aString, PRUint32 aLength,
 
   if (mFontMetrics)
   {
-    nsFont *font;
+    const nsFont *font;
     mFontMetrics->GetFont(font);
     PRUint8 deco = font->decorations;