diff --git a/pkgs/by-name/ne/netcdffortran/package.nix b/pkgs/by-name/ne/netcdffortran/package.nix
index 50c745633639..0891559c5b78 100644
--- a/pkgs/by-name/ne/netcdffortran/package.nix
+++ b/pkgs/by-name/ne/netcdffortran/package.nix
@@ -27,8 +27,10 @@ stdenv.mkDerivation (finalAttrs: {
 
   doCheck = true;
 
-  FFLAGS = [ "-std=legacy" ];
-  FCFLAGS = [ "-std=legacy" ];
+  env = {
+    FFLAGS = toString [ "-std=legacy" ];
+    FCFLAGS = toString [ "-std=legacy" ];
+  };
 
   meta = {
     description = "Fortran API to manipulate netcdf files";