diff --git a/cogl/cogl/driver/gl/gl/cogl-texture-driver-gl.c b/cogl/cogl/driver/gl/gl/cogl-texture-driver-gl.c
index 6990feff3..af50f103e 100644
--- a/cogl/cogl/driver/gl/gl/cogl-texture-driver-gl.c
+++ b/cogl/cogl/driver/gl/gl/cogl-texture-driver-gl.c
@@ -457,7 +457,8 @@ _cogl_texture_driver_upload_supported (CoglContext *ctx,
     case COGL_PIXEL_FORMAT_DEPTH_24_STENCIL_8:
     case COGL_PIXEL_FORMAT_ANY:
     case COGL_PIXEL_FORMAT_YUV:
-      return TRUE;
+      g_assert_not_reached ();
+      return FALSE;
     }
 
   g_assert_not_reached ();
diff --git a/cogl/cogl/driver/gl/gles/cogl-texture-driver-gles.c b/cogl/cogl/driver/gl/gles/cogl-texture-driver-gles.c
index 6c92f5880..bf4df399b 100644
--- a/cogl/cogl/driver/gl/gles/cogl-texture-driver-gles.c
+++ b/cogl/cogl/driver/gl/gles/cogl-texture-driver-gles.c
@@ -511,7 +511,8 @@ _cogl_texture_driver_upload_supported (CoglContext *ctx,
     case COGL_PIXEL_FORMAT_DEPTH_24_STENCIL_8:
     case COGL_PIXEL_FORMAT_ANY:
     case COGL_PIXEL_FORMAT_YUV:
-      return TRUE;
+      g_assert_not_reached ();
+      return FALSE;
     }
 
   g_assert_not_reached ();