diff --git a/bazel/variables.bzl b/bazel/variables.bzl
index 1d94a2aa..1d28c04a 100644
--- a/bazel/variables.bzl
+++ b/bazel/variables.bzl
@@ -15,11 +15,9 @@
 COPTS = select({
     "@bazel_tools//src/conditions:windows": [
         "/std:c++17",
-        "-DWITHOUT_ZLIB",
     ],
     "//conditions:default": [
         "-std=c++17",
-        "-DWITHOUT_ZLIB",
     ],
 })
 
diff --git a/src/foreign.cc b/src/foreign.cc
deleted file mode 100644
index 34335697..00000000
--- a/src/foreign.cc
+++ /dev/null
@@ -1,66 +0,0 @@
-// Copyright 2016-2019 Envoy Project Authors
-// Copyright 2020 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "include/proxy-wasm/wasm.h"
-
-#ifndef WITHOUT_ZLIB
-#include "zlib.h"
-#endif
-
-namespace proxy_wasm {
-namespace {
-
-#ifndef WITHOUT_ZLIB
-RegisterForeignFunction compressFunction(
-    "compress",
-    [](WasmBase &, std::string_view arguments,
-       std::function<void *(size_t size)> alloc_result) -> WasmResult {
-      unsigned long dest_len = compressBound(arguments.size());
-      std::unique_ptr<unsigned char[]> b(new unsigned char[dest_len]);
-      if (compress(b.get(), &dest_len, reinterpret_cast<const unsigned char *>(arguments.data()),
-                   arguments.size()) != Z_OK) {
-        return WasmResult::SerializationFailure;
-      }
-      auto result = alloc_result(dest_len);
-      memcpy(result, b.get(), dest_len);
-      return WasmResult::Ok;
-    });
-
-RegisterForeignFunction
-    uncompressFunction("uncompress",
-                       [](WasmBase &, std::string_view arguments,
-                          std::function<void *(size_t size)> alloc_result) -> WasmResult {
-                         unsigned long dest_len = arguments.size() * 2 + 2; // output estimate.
-                         while (1) {
-                           std::unique_ptr<unsigned char[]> b(new unsigned char[dest_len]);
-                           auto r =
-                               uncompress(b.get(), &dest_len,
-                                          reinterpret_cast<const unsigned char *>(arguments.data()),
-                                          arguments.size());
-                           if (r == Z_OK) {
-                             auto result = alloc_result(dest_len);
-                             memcpy(result, b.get(), dest_len);
-                             return WasmResult::Ok;
-                           }
-                           if (r != Z_MEM_ERROR) {
-                             return WasmResult::SerializationFailure;
-                           }
-                           dest_len = dest_len * 2;
-                         }
-                       });
-#endif
-
-} // namespace
-} // namespace proxy_wasm