diff --git a/pkgs/by-name/ep/epkowa/package.nix b/pkgs/by-name/ep/epkowa/package.nix
index 1f179ab71018..8a994baa8cd2 100644
--- a/pkgs/by-name/ep/epkowa/package.nix
+++ b/pkgs/by-name/ep/epkowa/package.nix
@@ -95,6 +95,8 @@ stdenv.mkDerivation rec {
   configureFlags = [
     "--enable-dependency-reduction"
     "--disable-frontend"
+    # fix build with gcc 15
+    "CFLAGS=-std=gnu17"
   ];
 
   postConfigure = ''