diff --git a/pkgs/by-name/ig/igprof/package.nix b/pkgs/by-name/ig/igprof/package.nix
index 3cb0885b43f7..a0fc1c0a5e58 100644
--- a/pkgs/by-name/ig/igprof/package.nix
+++ b/pkgs/by-name/ig/igprof/package.nix
@@ -32,7 +32,8 @@ stdenv.mkDerivation (finalAttrs: {
     pcre
   ];
   nativeBuildInputs = [ cmake ];
-  CXXFLAGS = [
+
+  env.CXXFLAGS = toString [
     "-fPIC"
     "-O2"
     "-w"