diff --git a/pkgs/by-name/or/orthanc-framework/package.nix b/pkgs/by-name/or/orthanc-framework/package.nix
index cb995af664eb..4851f4857cc4 100644
--- a/pkgs/by-name/or/orthanc-framework/package.nix
+++ b/pkgs/by-name/or/orthanc-framework/package.nix
@@ -23,7 +23,7 @@ stdenv.mkDerivation (finalAttrs: {
     icu
   ];
 
-  NIX_LDFLAGS = lib.strings.concatStringsSep " " [
+  env.NIX_LDFLAGS = toString [
     "-L${lib.getLib zlib}"
     "-lz"
     "-L${lib.getLib gtest}"