--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -1128,18 +1128,20 @@ gfxWindowsPlatform::FontsPrefsChanged(co
     if (clearTextFontCaches) {
         gfxFontCache *fc = gfxFontCache::GetCache();
         if (fc) {
             fc->Flush();
         }
     }
 }
 
-#define ENHANCED_CONTRAST_REGISTRY_KEY \
-    HKEY_CURRENT_USER, "Software\\Microsoft\\Avalon.Graphics\\DISPLAY1\\EnhancedContrastLevel"
+#define DISPLAY1_REGISTRY_KEY \
+    HKEY_CURRENT_USER, "Software\\Microsoft\\Avalon.Graphics\\DISPLAY1"
+
+#define ENHANCED_CONTRAST_VALUE_NAME "EnhancedContrastLevel"
 
 void
 gfxWindowsPlatform::SetupClearTypeParams()
 {
     if (GetDWriteFactory()) {
         // any missing prefs will default to invalid (-1) and be ignored;
         // out-of-range values will also be ignored
         FLOAT gamma = -1.0;
@@ -1196,20 +1198,24 @@ gfxWindowsPlatform::SetupClearTypeParams
         RefPtr<IDWriteRenderingParams> defaultRenderingParams;
         GetDWriteFactory()->CreateRenderingParams(getter_AddRefs(defaultRenderingParams));
         // For EnhancedContrast, we override the default if the user has not set it
         // in the registry (by using the ClearType Tuner).
         if (contrast >= 0.0 && contrast <= 10.0) {
             contrast = contrast;
         } else {
             HKEY hKey;
-            if (RegOpenKeyExA(ENHANCED_CONTRAST_REGISTRY_KEY,
-                              0, KEY_READ, &hKey) == ERROR_SUCCESS)
-            {
-                contrast = defaultRenderingParams->GetEnhancedContrast();
+            LONG res = RegOpenKeyExA(DISPLAY1_REGISTRY_KEY,
+                                     0, KEY_READ, &hKey);
+            if (res == ERROR_SUCCESS) {
+                res = RegQueryValueExA(hKey, ENHANCED_CONTRAST_VALUE_NAME,
+                                       nullptr, nullptr, nullptr, nullptr);
+                if (res == ERROR_SUCCESS) {
+                    contrast = defaultRenderingParams->GetEnhancedContrast();
+                }
                 RegCloseKey(hKey);
             } else {
                 contrast = 1.0;
             }
         }
 
         // For parameters that have not been explicitly set,
         // we copy values from default params (or our overridden value for contrast)