diff --git a/lib/cpp/test/Makefile.am b/lib/cpp/test/Makefile.am
index cd401c0..a744039 100644
--- a/lib/cpp/test/Makefile.am
+++ b/lib/cpp/test/Makefile.am
@@ -424,6 +424,9 @@
 clean-local:
 	$(RM) gen-cpp/*
 
+distdir:
+	$(MAKE) $(AM_MAKEFLAGS) distdir-am
+
 EXTRA_DIST = \
 	concurrency \
 	processor \