--- a/dom/canvas/WebGL2ContextState.cpp
+++ b/dom/canvas/WebGL2ContextState.cpp
@@ -53,47 +53,54 @@ WebGL2Context::GetParameter(JSContext* c
     case LOCAL_GL_MAX_FRAGMENT_UNIFORM_COMPONENTS:
     case LOCAL_GL_MAX_PROGRAM_TEXEL_OFFSET:
     case LOCAL_GL_MAX_SAMPLES:
     case LOCAL_GL_MAX_TEXTURE_LOD_BIAS:
     case LOCAL_GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS:
     case LOCAL_GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS:
     case LOCAL_GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS:
     case LOCAL_GL_MAX_UNIFORM_BUFFER_BINDINGS:
-    case LOCAL_GL_MAX_VARYING_COMPONENTS:
     case LOCAL_GL_MAX_VERTEX_OUTPUT_COMPONENTS:
     case LOCAL_GL_MAX_VERTEX_UNIFORM_BLOCKS:
     case LOCAL_GL_MAX_VERTEX_UNIFORM_COMPONENTS:
     case LOCAL_GL_MIN_PROGRAM_TEXEL_OFFSET:
     case LOCAL_GL_PACK_ROW_LENGTH:
     case LOCAL_GL_PACK_SKIP_PIXELS:
     case LOCAL_GL_PACK_SKIP_ROWS:
     case LOCAL_GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT:
     case LOCAL_GL_UNPACK_IMAGE_HEIGHT:
     case LOCAL_GL_UNPACK_ROW_LENGTH: {
       GLint val;
       gl->fGetIntegerv(pname, &val);
       return JS::Int32Value(val);
     }
 
+    case LOCAL_GL_MAX_VARYING_COMPONENTS: {
+      // On OS X Core Profile this is buggy.  The spec says that the
+      // value is 4 * GL_MAX_VARYING_VECTORS
+      GLint val;
+      gl->fGetIntegerv(LOCAL_GL_MAX_VARYING_VECTORS, &val);
+      return JS::Int32Value(4*val);
+    }
+
     /* GLint64 */
     case LOCAL_GL_MAX_CLIENT_WAIT_TIMEOUT_WEBGL:
       return JS::NumberValue(0); // TODO
 
     case LOCAL_GL_MAX_ELEMENT_INDEX:
     case LOCAL_GL_MAX_COMBINED_FRAGMENT_UNIFORM_COMPONENTS:
     case LOCAL_GL_MAX_COMBINED_VERTEX_UNIFORM_COMPONENTS:
     case LOCAL_GL_MAX_UNIFORM_BLOCK_SIZE: {
       GLint64 val;
       gl->fGetInteger64v(pname, &val);
       return JS::DoubleValue(static_cast<double>(val));
     }
 
 
-      // GLuint64
+    /* GLuint64 */
     case LOCAL_GL_MAX_SERVER_WAIT_TIMEOUT: {
       GLuint64 val;
       gl->fGetInteger64v(pname, (GLint64*) &val);
       return JS::DoubleValue(static_cast<double>(val));
     }
 
     case LOCAL_GL_COPY_READ_BUFFER_BINDING:
       return WebGLObjectAsJSValue(cx, mBoundCopyReadBuffer.get(), rv);