diff --git a/pkgs/by-name/ri/river-bnf/package.nix b/pkgs/by-name/ri/river-bnf/package.nix
index 717c4d180276..a7316306bb85 100644
--- a/pkgs/by-name/ri/river-bnf/package.nix
+++ b/pkgs/by-name/ri/river-bnf/package.nix
@@ -18,6 +18,9 @@ stdenv.mkDerivation {
     hash = "sha256-rm9Nt3WLgq9QOXzrkYBGp45EALNYFTQGInxfYIN0XcU=";
   };
 
+  # Fix build with gcc 15
+  env.NIX_CFLAGS_COMPILE = "-std=gnu17";
+
   nativeBuildInputs = [
     wayland-scanner
   ];