diff --git a/internal/gitaly/service/operations/update_with_hooks.go b/internal/gitaly/service/operations/update_with_hooks.go
index ba90634bc46eceff5bac37ae99b53a8ea36c0851..615f8217eb119a9e4fa3385dae5abe49cf3807fc 100644
--- a/internal/gitaly/service/operations/update_with_hooks.go
+++ b/internal/gitaly/service/operations/update_with_hooks.go
@@ -62,6 +62,10 @@ func (s *Server) updateReferenceWithHooks(ctx context.Context, repo *gitalypb.Re
 	changes := fmt.Sprintf("%s %s %s\n", oldrev, newrev, reference)
 	var stdout, stderr bytes.Buffer
 
+	if s.hookManager == nil {
+		// See https://gitlab.com/gitlab-org/gitaly/-/merge_requests/2911#note_468836913
+		panic("The hookManager must be set up already! Did you migrate non-hook-supporting code from Ruby to Go?")
+	}
 	if err := s.hookManager.PreReceiveHook(ctx, repo, env, strings.NewReader(changes), &stdout, &stderr); err != nil {
 		msg := hookErrorFromStdoutAndStderr(stdout.String(), stderr.String())
 		return preReceiveError{message: msg}