diff --git a/nixos/modules/services/misc/gitlab.nix b/nixos/modules/services/misc/gitlab.nix
index 09c3a89d6a6..bd7bb6214bf 100644
--- a/nixos/modules/services/misc/gitlab.nix
+++ b/nixos/modules/services/misc/gitlab.nix
@@ -184,6 +184,7 @@ let
         domain: "${cfg.smtp.domain}",
         ${optionalString (cfg.smtp.authentication != null) "authentication: :${cfg.smtp.authentication},"}
         enable_starttls_auto: ${toString cfg.smtp.enableStartTLSAuto},
+        ca_file: "/etc/ssl/certs/ca-certificates.crt",
         openssl_verify_mode: '${cfg.smtp.opensslVerifyMode}'
       }
     end