diff --git a/drmdisplaycompositor.h b/drmdisplaycompositor.h
index f1965fb..ed6c5f9 100644
--- a/drmdisplaycompositor.h
+++ b/drmdisplaycompositor.h
@@ -98,6 +98,9 @@
     return &squash_state_;
   }
 
+  bool uses_GL() {
+    return !!pre_compositor_;
+  }
  private:
   struct ModeState {
     bool needs_modeset = false;