diff --git a/pkgs/package-overrides.nix b/pkgs/package-overrides.nix
index 29b769dd..fd3ed869 100644
--- a/pkgs/package-overrides.nix
+++ b/pkgs/package-overrides.nix
@@ -359,7 +359,9 @@ in
         ourPatches ++ upstreamPatches;
 
       nativeBuildInputs = attrs.nativeBuildInputs ++ [
+        # Tarballs ship pre-generated parser files.
         pkgs.bison
+        pkgs.flex
       ];
 
       postPatch = ''
@@ -470,11 +472,20 @@ in
 
     tokenizer =
       prev.extensions.tokenizer.overrideAttrs (attrs: {
-        nativeBuildInputs = attrs.nativeBuildInputs or [ ] ++ lib.optionals isBuiltFromGit [
+        nativeBuildInputs = attrs.nativeBuildInputs ++ [
           # Tarballs ship pre-generated parser files.
           pkgs.bison
           pkgs.flex
         ];
+        postPatch = ''
+          echo '
+            # TODO: Add explanation here.
+            # See https://github.com/fossar/nix-phps/pull/104#issuecomment-1113964195
+            PHP_PROG_BISON([3.0.0])
+            PHP_PROG_RE2C([0.13.4])
+          ' | cat - ext/tokenizer/config.m4 > ext/tokenizer/config.m4.tmp
+          mv ext/tokenizer/config.m4{.tmp,}
+        '';
       });
 
     wddx =