diff --git a/conformance/binary_json_conformance_suite.cc b/conformance/binary_json_conformance_suite.cc
index 745a400613..ee21790841 100644
--- a/conformance/binary_json_conformance_suite.cc
+++ b/conformance/binary_json_conformance_suite.cc
@@ -45,6 +45,7 @@
 #include "json/json.h"
 #include "conformance/conformance.pb.h"
 #include "conformance_test.h"
+#include "google/protobuf/endian.h"
 #include "google/protobuf/test_messages_proto2.pb.h"
 #include "google/protobuf/test_messages_proto3.pb.h"
 #include "google/protobuf/wire_format_lite.h"
@@ -58,6 +59,7 @@ using google::protobuf::Descriptor;
 using google::protobuf::FieldDescriptor;
 using google::protobuf::Message;
 using google::protobuf::internal::WireFormatLite;
+using google::protobuf::internal::little_endian::FromHost;
 using google::protobuf::util::NewTypeResolverForDescriptorPool;
 using proto2_messages::TestAllTypesProto2;
 using protobuf_test_messages::proto3::TestAllTypesProto3;
@@ -117,9 +119,18 @@ string longvarint(uint64_t x, int extra) {
   return string(buf, len);
 }
 
-// TODO: proper byte-swapping for big-endian machines.
-string fixed32(void* data) { return string(static_cast<char*>(data), 4); }
-string fixed64(void* data) { return string(static_cast<char*>(data), 8); }
+string fixed32(void* data) {
+  uint32_t data_le;
+  std::memcpy(&data_le, data, 4);
+  data_le = FromHost(data_le);
+  return string(reinterpret_cast<char*>(&data_le), 4);
+}
+string fixed64(void* data) {
+  uint64_t data_le;
+  std::memcpy(&data_le, data, 8);
+  data_le = FromHost(data_le);
+  return string(reinterpret_cast<char*>(&data_le), 8);
+}
 
 string delim(const string& buf) {
   return absl::StrCat(varint(buf.size()), buf);
@@ -3100,12 +3111,8 @@ void BinaryAndJsonConformanceSuite::RunJsonTestsForValue() {
       },
       true);
   RunValidJsonTestWithValidator(
-      "NullValueInNormalMessage", RECOMMENDED,
-      R"({"optionalNullValue": null})",
-      [](const Json::Value& value) {
-        return value.empty();
-      },
-      true);
+      "NullValueInNormalMessage", RECOMMENDED, R"({"optionalNullValue": null})",
+      [](const Json::Value& value) { return value.empty(); }, true);
   ExpectSerializeFailureForJson("ValueRejectNanNumberValue", RECOMMENDED,
                                 "optional_value: { number_value: nan}");
   ExpectSerializeFailureForJson("ValueRejectInfNumberValue", RECOMMENDED,
diff --git a/conformance/conformance_cpp.cc b/conformance/conformance_cpp.cc
index 2fc9424ec8..a7d9c2e014 100644
--- a/conformance/conformance_cpp.cc
+++ b/conformance/conformance_cpp.cc
@@ -46,6 +46,7 @@
 #include "absl/status/statusor.h"
 #include "conformance/conformance.pb.h"
 #include "conformance/conformance.pb.h"
+#include "google/protobuf/endian.h"
 #include "google/protobuf/test_messages_proto2.pb.h"
 #include "google/protobuf/test_messages_proto3.pb.h"
 #include "google/protobuf/test_messages_proto3.pb.h"
@@ -228,6 +229,7 @@ absl::StatusOr<bool> Harness::ServeConformanceRequest() {
     // EOF means we're done.
     return true;
   }
+  in_len = internal::little_endian::ToHost(in_len);
 
   std::string serialized_input;
   serialized_input.resize(in_len);
@@ -242,9 +244,12 @@ absl::StatusOr<bool> Harness::ServeConformanceRequest() {
   std::string serialized_output;
   response->SerializeToString(&serialized_output);
 
-  uint32_t out_len = static_cast<uint32_t>(serialized_output.size());
+  uint32_t out_len = internal::little_endian::FromHost(
+      static_cast<uint32_t>(serialized_output.size()));
+
   RETURN_IF_ERROR(WriteFd(STDOUT_FILENO, &out_len, sizeof(out_len)));
-  RETURN_IF_ERROR(WriteFd(STDOUT_FILENO, serialized_output.data(), out_len));
+  RETURN_IF_ERROR(WriteFd(STDOUT_FILENO, serialized_output.data(),
+                          serialized_output.size()));
 
   if (verbose_) {
     ABSL_LOG(INFO) << "conformance-cpp: request=" << request.ShortDebugString()
diff --git a/conformance/conformance_test_runner.cc b/conformance/conformance_test_runner.cc
index 19497a1e1d..d22213acaf 100644
--- a/conformance/conformance_test_runner.cc
+++ b/conformance/conformance_test_runner.cc
@@ -69,6 +69,7 @@
 #include "absl/strings/str_format.h"
 #include "conformance/conformance.pb.h"
 #include "conformance_test.h"
+#include "google/protobuf/endian.h"
 
 using conformance::ConformanceResponse;
 using google::protobuf::ConformanceTestSuite;
@@ -155,7 +156,8 @@ void ForkPipeRunner::RunTest(const std::string &test_name,
   }
   current_test_name_ = test_name;
 
-  uint32_t len = request.size();
+  uint32_t len =
+      internal::little_endian::FromHost(static_cast<uint32_t>(request.size()));
   CheckedWrite(write_fd_, &len, sizeof(uint32_t));
   CheckedWrite(write_fd_, request.c_str(), request.size());
 
@@ -190,6 +192,7 @@ void ForkPipeRunner::RunTest(const std::string &test_name,
     return;
   }
 
+  len = internal::little_endian::ToHost(len);
   response->resize(len);
   CheckedRead(read_fd_, (void *)response->c_str(), len);
 }