diff --git a/git.c b/git.c
index d6f17db91..78ed403ed 100644
--- a/git.c
+++ b/git.c
@@ -391,6 +391,8 @@ static int cmd_log(int argc, const char **argv, char **envp)
 		if (do_diff)
 			log_tree_commit(&opt, commit);
 		shown = 1;
+		free(commit->buffer);
+		commit->buffer = NULL;
 	}
 	free(buf);
 	return 0;