diff --git a/Tests/CustomCommand/foo.h.in b/Tests/CustomCommand/foo.h.in
index d6a4a56ce..d7721a2a5 100644
--- a/Tests/CustomCommand/foo.h.in
+++ b/Tests/CustomCommand/foo.h.in
@@ -1 +1 @@
-// Empty header file just used to test header generation.
+/* Empty header file just used to test header generation. */