diff --git a/builtin-shortlog.c b/builtin-shortlog.c
index 3322c3a2ee..3fc43dd7dd 100644
--- a/builtin-shortlog.c
+++ b/builtin-shortlog.c
@@ -188,7 +188,8 @@ static void read_from_stdin(struct path_list *list)
 				bob = buffer + strlen(buffer);
 			else {
 				offset = 8;
-				if (isspace(bob[-1]))
+				while (buffer + offset < bob &&
+				       isspace(bob[-1]))
 					bob--;
 			}