diff --git a/gfx/thebes/gfxPlatformFontList.cpp b/gfx/thebes/gfxPlatformFontList.cpp
index d9504cf2d951..c68e471643c7 100644
--- a/gfx/thebes/gfxPlatformFontList.cpp
+++ b/gfx/thebes/gfxPlatformFontList.cpp
@@ -1721,6 +1721,7 @@ gfxPlatformFontList::ClearLangGroupPrefFonts()
         }
     }
     mCJKPrefLangs.Clear();
+    mEmojiPrefFont = nullptr;
 }
 
 // Support for memory reporting