diff --git a/internal/gitaly/service/diff/commit_diff.go b/internal/gitaly/service/diff/commit_diff.go
index c9d97e7ebcac8492e21653ddc70e84e7e9a2d1dd..1a6e2d2a868a9de448a8f1eec6fa6dc8c31b430b 100644
--- a/internal/gitaly/service/diff/commit_diff.go
+++ b/internal/gitaly/service/diff/commit_diff.go
@@ -43,6 +43,7 @@ func (s *server) CommitDiff(in *gitalypb.CommitDiffRequest, stream gitalypb.Diff
 			git.Flag{Name: fmt.Sprintf("--abbrev=%d", objectHash.EncodedLen())},
 			git.Flag{Name: "--full-index"},
 			git.Flag{Name: "--find-renames=30%"},
+			git.Flag{Name: "--root"},
 		},
 		Args: []string{leftSha, rightSha},
 	}