diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index a48e7e4..bfd5a11 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -57,7 +57,7 @@
     static status_t writeToParcel(const sp<Surface>& surface, Parcel* parcel);
     static sp<Surface> readFromParcel(const Parcel& data);
 
-    bool isValid(const sp<Surface>& surface) const {
+    static bool isValid(const sp<Surface>& surface) {
         return surface != NULL && surface->getIGraphicBufferProducer() != NULL;
     }