diff --git a/pkgs/by-name/or/orthanc-plugin-dicomweb/package.nix b/pkgs/by-name/or/orthanc-plugin-dicomweb/package.nix
index 5670e6bf3e12..c34a5d44141f 100644
--- a/pkgs/by-name/or/orthanc-plugin-dicomweb/package.nix
+++ b/pkgs/by-name/or/orthanc-plugin-dicomweb/package.nix
@@ -80,7 +80,7 @@ stdenv.mkDerivation (finalAttrs: {
 
   strictDeps = true;
 
-  NIX_LDFLAGS = lib.strings.concatStringsSep " " [
+  env.NIX_LDFLAGS = toString [
     "-L${lib.getLib gtest}"
     "-lgtest"
   ];