diff --git a/pkgs/by-name/cb/cbmbasic/package.nix b/pkgs/by-name/cb/cbmbasic/package.nix
index 38fd85923edc..f6019dae8d97 100644
--- a/pkgs/by-name/cb/cbmbasic/package.nix
+++ b/pkgs/by-name/cb/cbmbasic/package.nix
@@ -16,6 +16,11 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-aA/ivRap+aDd2wi6KWXam9eP/21lOn6OWTeZ4i/S9Bs=";
   };
 
+  postPatch = ''
+    substituteInPlace cbmbasic.c \
+      --replace-fail "typedef unsigned char bool;" ""
+  '';
+
   installPhase = ''
     runHook preInstall