diff --git a/cogl/cogl-texture-2d-private.h b/cogl/cogl-texture-2d-private.h
index fc9db8148..33c71efe0 100644
--- a/cogl/cogl-texture-2d-private.h
+++ b/cogl/cogl-texture-2d-private.h
@@ -67,4 +67,15 @@ _cogl_texture_2d_new_from_bitmap (CoglHandle       bmp_handle,
                                   CoglTextureFlags flags,
                                   CoglPixelFormat  internal_format);
 
+/*
+ * _cogl_texture_2d_externally_modified:
+ * @handle: A handle to a 2D texture
+ *
+ * This should be called whenever the texture is modified other than
+ * by using cogl_texture_set_region. It will cause the mipmaps to be
+ * invalidated
+ */
+void
+_cogl_texture_2d_externally_modified (CoglHandle handle);
+
 #endif /* __COGL_TEXTURE_2D_H */
diff --git a/cogl/cogl-texture-2d.c b/cogl/cogl-texture-2d.c
index a7bcbf322..3c33a7557 100644
--- a/cogl/cogl-texture-2d.c
+++ b/cogl/cogl-texture-2d.c
@@ -320,6 +320,15 @@ _cogl_texture_2d_new_from_bitmap (CoglHandle       bmp_handle,
   return _cogl_texture_2d_handle_new (tex_2d);
 }
 
+void
+_cogl_texture_2d_externally_modified (CoglHandle handle)
+{
+  if (!cogl_is_texture_2d (handle))
+    return;
+
+  COGL_TEXTURE_2D (handle)->mipmaps_dirty = TRUE;
+}
+
 static int
 _cogl_texture_2d_get_max_waste (CoglTexture *tex)
 {