--- a/dom/canvas/WebGLContextExtensions.cpp
+++ b/dom/canvas/WebGLContextExtensions.cpp
@@ -123,19 +123,21 @@ WebGLContext::IsExtensionSupported(WebGL
         return gl->IsSupported(gl::GLFeature::texture_float_linear);
 
     // WEBGL_
     case WebGLExtensionID::WEBGL_compressed_texture_astc:
         return WebGLExtensionCompressedTextureASTC::IsSupported(this);
     case WebGLExtensionID::WEBGL_compressed_texture_atc:
         return gl->IsExtensionSupported(gl::GLContext::AMD_compressed_ATC_texture);
     case WebGLExtensionID::WEBGL_compressed_texture_etc:
-        return gl->IsSupported(gl::GLFeature::ES3_compatibility);
+        return gl->IsSupported(gl::GLFeature::ES3_compatibility) &&
+               !gl->IsANGLE();
     case WebGLExtensionID::WEBGL_compressed_texture_etc1:
-        return gl->IsExtensionSupported(gl::GLContext::OES_compressed_ETC1_RGB8_texture);
+        return gl->IsExtensionSupported(gl::GLContext::OES_compressed_ETC1_RGB8_texture) &&
+               !gl->IsANGLE();
     case WebGLExtensionID::WEBGL_compressed_texture_pvrtc:
         return gl->IsExtensionSupported(gl::GLContext::IMG_texture_compression_pvrtc);
     case WebGLExtensionID::WEBGL_compressed_texture_s3tc:
         if (gl->IsExtensionSupported(gl::GLContext::EXT_texture_compression_s3tc))
             return true;
 
         return gl->IsExtensionSupported(gl::GLContext::EXT_texture_compression_dxt1) &&
                gl->IsExtensionSupported(gl::GLContext::ANGLE_texture_compression_dxt3) &&