diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c
index 512f44add89f41fae6706114c5ce497279a4f107..3e6208f773e28f434539dbfd4c3de0cb929c9e58 100644
--- a/drivers/gpu/drm/udl/udl_connector.c
+++ b/drivers/gpu/drm/udl/udl_connector.c
@@ -57,6 +57,14 @@ static int udl_get_modes(struct drm_connector *connector)
 
 	edid = (struct edid *)udl_get_edid(udl);
 
+	/*
+	 * We only read the main block, but if the monitor reports extension
+	 * blocks then the drm edid code expects them to be present, so patch
+	 * the extension count to 0.
+	 */
+	edid->checksum += edid->extensions;
+	edid->extensions = 0;
+
 	drm_mode_connector_update_edid_property(connector, edid);
 	ret = drm_add_edid_modes(connector, edid);
 	kfree(edid);