--- a/gfx/thebes/gfxDWriteFonts.cpp
+++ b/gfx/thebes/gfxDWriteFonts.cpp
@@ -663,17 +663,17 @@ already_AddRefed<ScaledFont> gfxDWriteFo
             UsingClearType()
                 ? (forceGDI ? gfxWindowsPlatform::TEXT_RENDERING_GDI_CLASSIC
                             : gfxWindowsPlatform::TEXT_RENDERING_NORMAL)
                 : gfxWindowsPlatform::TEXT_RENDERING_NO_CLEARTYPE);
 
     DWRITE_RENDERING_MODE renderingMode = params->GetRenderingMode();
     FLOAT gamma = params->GetGamma();
     FLOAT contrast = params->GetEnhancedContrast();
-    if (forceGDI) {
+    if (forceGDI || renderingMode == DWRITE_RENDERING_MODE_GDI_CLASSIC) {
       renderingMode = DWRITE_RENDERING_MODE_GDI_CLASSIC;
       gamma = GetSystemGDIGamma();
       contrast = 0.0f;
     }
 
     const gfxFontStyle* fontStyle = GetStyle();
     mAzureScaledFont = Factory::CreateScaledFontForDWriteFont(
         mFontFace, fontStyle, GetUnscaledFont(), GetAdjustedSize(),