diff --git a/src/index.ts b/src/index.ts
index 5fbaf0d..e8a0edd 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -287,11 +287,11 @@ export const getGPUTier = async ({
       return toResult(0, 'WEBGL_UNSUPPORTED');
     }
 
-    const debugRendererInfo = gl.getExtension('WEBGL_debug_renderer_info');
+    const debugRendererInfo = deviceInfo?.isFirefox ? null : gl.getExtension('WEBGL_debug_renderer_info');
 
-    if (debugRendererInfo) {
-      renderer = gl.getParameter(debugRendererInfo.UNMASKED_RENDERER_WEBGL);
-    }
+    renderer = debugRendererInfo
+      ? gl.getParameter(debugRendererInfo.UNMASKED_RENDERER_WEBGL)
+      : gl.getParameter(gl.RENDERER);
 
     if (!renderer) {
       return toResult(1, 'FALLBACK');
diff --git a/src/internal/deviceInfo.ts b/src/internal/deviceInfo.ts
index 5b39d26..2c32a1a 100644
--- a/src/internal/deviceInfo.ts
+++ b/src/internal/deviceInfo.ts
@@ -23,5 +23,6 @@ export const deviceInfo = (() => {
     isIpad,
     isMobile: isAndroid || isIOS || isIpad,
     isSafari12: /Version\/12.+Safari/.test(userAgent),
+    isFirefox: /Firefox/.test(userAgent)
   };
 })();