diff --git a/pkgs/servers/apcupsd/default.nix b/pkgs/servers/apcupsd/default.nix
index 8e25bdd87f0..ad8685d3d42 100644
--- a/pkgs/servers/apcupsd/default.nix
+++ b/pkgs/servers/apcupsd/default.nix
@@ -2,6 +2,8 @@
 , enableCgiScripts ? true, gd
 }:
 
+assert enableCgiScripts -> gd != null;
+
 stdenv.mkDerivation rec {
   pname = "apcupsd";
   name = "${pname}-3.14.12";