diff --git a/commit.h b/commit.h
index afd14f3..9c12abb 100644
--- a/commit.h
+++ b/commit.h
@@ -355,7 +355,7 @@ extern const char *find_commit_header(const char *msg, const char *key,
 				      size_t *out_len);
 
 /* Find the end of the log message, the right place for a new trailer. */
-extern int ignore_non_trailer(struct strbuf *sb);
+extern int ignore_non_trailer(const char *buf, size_t len);
 
 typedef void (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
 				 void *cb_data);