diff --git a/drmdisplaycomposition.h b/drmdisplaycomposition.h
index 814ca24..2ac93e0 100644
--- a/drmdisplaycomposition.h
+++ b/drmdisplaycomposition.h
@@ -23,6 +23,7 @@
 #include "glworker.h"
 #include "importer.h"
 
+#include <sstream>
 #include <vector>
 
 #include <hardware/gralloc.h>
@@ -123,6 +124,8 @@
     return importer_;
   }
 
+  void Dump(std::ostringstream *out) const;
+
  private:
   bool validate_composition_type(DrmCompositionType desired);