diff --git a/pkgs/development/coq-modules/interval/default.nix b/pkgs/development/coq-modules/interval/default.nix
index e7b4662f2c2b..8efe8b1f7589 100644
--- a/pkgs/development/coq-modules/interval/default.nix
+++ b/pkgs/development/coq-modules/interval/default.nix
@@ -65,7 +65,9 @@ mkCoqDerivation rec {
       mathcomp-boot
       mathcomp-fingroup
     ]
-    ++ lib.optionals (lib.versions.isGe "4.2.0" defaultVersion) [ gnuplot_qt ];
+    ++ lib.optionals (defaultVersion != null && lib.versions.isGe "4.2.0" defaultVersion) [
+      gnuplot_qt
+    ];
   useMelquiondRemake.logpath = "Interval";
   mlPlugin = true;