Fix compiler warning about void return in non void method.
diff --git a/openbsc/tests/debug/debug_test.c b/openbsc/tests/debug/debug_test.c
index 695d65c..f3e4837 100644
--- a/openbsc/tests/debug/debug_test.c
+++ b/openbsc/tests/debug/debug_test.c
@@ -38,4 +38,6 @@
 	DEBUGP(DRLL, "You should see this\n");
 	DEBUGP(DCC, "You should see this\n");
 	DEBUGP(DMM, "You should not see this\n");
+
+	return 0;
 }