diff --git a/builtin/commit.c b/builtin/commit.c
index d8abbe4..583bf04 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -890,7 +890,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	s->hints = 0;
 
 	if (clean_message_contents)
-		strbuf_stripspace(&sb, '\0');
+		strbuf_stripspace(&sb, NULL);
 
 	if (signoff)
 		append_signoff(&sb, ignored_log_message_bytes(sb.buf, sb.len), 0);