diff --git a/pkgs/by-name/li/libmhash/package.nix b/pkgs/by-name/li/libmhash/package.nix
index 1c3ed89fba10..89cbb8c679d3 100644
--- a/pkgs/by-name/li/libmhash/package.nix
+++ b/pkgs/by-name/li/libmhash/package.nix
@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
   patches = [ ./autotools-define-conflict-debian-fix.patch ];
 
   # Fix build with gcc15
-  env.NIX_CFLAGS_COMPILE = "-std=gnu17";
+  configureFlags = [ "CFLAGS=-std=gnu17" ];
 
   meta = {
     description = "Hash algorithms library";