diff --git a/models/pull.go b/models/pull.go
index 94bd7930ff..1db0a89741 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -495,7 +495,7 @@ func (pr *PullRequest) getMergeCommit() (*git.Commit, error) {
 
 	if err != nil {
 		// Errors are signaled by a non-zero status that is not 1
-		if err.Error() == "exit status 1" {
+		if strings.Contains(err.Error(), "exit status 1") {
 			return nil, nil
 		}
 		return nil, fmt.Errorf("git merge-base --is-ancestor: %v %v", stderr, err)