diff --git a/pkgs/applications/science/electronics/openems/default.nix b/pkgs/applications/science/electronics/openems/default.nix
index 64afe3222c2d..e7b947450acc 100644
--- a/pkgs/applications/science/electronics/openems/default.nix
+++ b/pkgs/applications/science/electronics/openems/default.nix
@@ -15,13 +15,10 @@
 , withQcsxcad ? true
 , withMPI ? false
 , withHyp2mat ? true
-, qcsxcad ? null
-, hyp2mat ? null
+, qcsxcad
+, hyp2mat
 }:
 
-assert withQcsxcad -> qcsxcad != null;
-assert withHyp2mat -> hyp2mat != null;
-
 stdenv.mkDerivation {
   pname = "openems";
   version = "unstable-2020-02-15";
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 5d05d615a76f..cf569ede7b0b 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -31177,7 +31177,9 @@ with pkgs;
 
   ngspice = callPackage ../applications/science/electronics/ngspice { };
 
-  openems = callPackage ../applications/science/electronics/openems { };
+  openems = callPackage ../applications/science/electronics/openems {
+    qcsxcad = libsForQt5.qcsxcad;
+  };
 
   openroad = libsForQt5.callPackage ../applications/science/electronics/openroad { };