diff --git a/sandboxed_api/sandbox2/buffer.cc b/sandboxed_api/sandbox2/buffer.cc
index c494061..81dabcf 100644
--- a/sandboxed_api/sandbox2/buffer.cc
+++ b/sandboxed_api/sandbox2/buffer.cc
@@ -54,7 +54,7 @@ absl::StatusOr<std::unique_ptr<Buffer>> Buffer::CreateFromFd(int fd) {
 
 // Creates a new Buffer of the specified size, backed by a temporary file that
 // will be immediately deleted.
-absl::StatusOr<std::unique_ptr<Buffer>> Buffer::CreateWithSize(int64 size) {
+absl::StatusOr<std::unique_ptr<Buffer>> Buffer::CreateWithSize(size_t size) {
   int fd;
   if (!util::CreateMemFd(&fd)) {
     return absl::InternalError("Could not create buffer temp file");
diff --git a/sandboxed_api/sandbox2/buffer.h b/sandboxed_api/sandbox2/buffer.h
index d6024b5..e9e9bc3 100644
--- a/sandboxed_api/sandbox2/buffer.h
+++ b/sandboxed_api/sandbox2/buffer.h
@@ -41,7 +41,7 @@ class Buffer final {
 
   // Creates a new Buffer of the specified size, backed by a temporary file that
   // will be immediately deleted.
-  static absl::StatusOr<std::unique_ptr<Buffer>> CreateWithSize(int64 size);
+  static absl::StatusOr<std::unique_ptr<Buffer>> CreateWithSize(size_t size);
 
   // Returns a pointer to the buffer, which is read/write.
   uint8_t* data() const { return buf_; }
diff --git a/sandboxed_api/sandbox2/comms.h b/sandboxed_api/sandbox2/comms.h
index c3fac21..fca8c53 100644
--- a/sandboxed_api/sandbox2/comms.h
+++ b/sandboxed_api/sandbox2/comms.h
@@ -128,10 +128,10 @@ class Comms {
   bool SendUint32(uint32_t v) { return SendGeneric(v, kTagUint32); }
   bool RecvInt32(int32_t* v) { return RecvIntGeneric(v, kTagInt32); }
   bool SendInt32(int32_t v) { return SendGeneric(v, kTagInt32); }
-  bool RecvUint64(uint64* v) { return RecvIntGeneric(v, kTagUint64); }
-  bool SendUint64(uint64 v) { return SendGeneric(v, kTagUint64); }
-  bool RecvInt64(int64* v) { return RecvIntGeneric(v, kTagInt64); }
-  bool SendInt64(int64 v) { return SendGeneric(v, kTagInt64); }
+  bool RecvUint64(uint64_t* v) { return RecvIntGeneric(v, kTagUint64); }
+  bool SendUint64(uint64_t v) { return SendGeneric(v, kTagUint64); }
+  bool RecvInt64(int64_t* v) { return RecvIntGeneric(v, kTagInt64); }
+  bool SendInt64(int64_t v) { return SendGeneric(v, kTagInt64); }
   bool RecvBool(bool* v) { return RecvIntGeneric(v, kTagBool); }
   bool SendBool(bool v) { return SendGeneric(v, kTagBool); }
   bool RecvString(std::string* v);
diff --git a/sandboxed_api/sandbox2/comms_test.cc b/sandboxed_api/sandbox2/comms_test.cc
index 496045e..bb8eedd 100644
--- a/sandboxed_api/sandbox2/comms_test.cc
+++ b/sandboxed_api/sandbox2/comms_test.cc
@@ -174,13 +174,13 @@ TEST_F(CommsTest, TestSendRecv64) {
     ASSERT_THAT(comms->SendUint64(1099511627776ULL), IsTrue());
 
     // Recv Int64.
-    int64 tmp64;
+    int64_t tmp64;
     ASSERT_THAT(comms->RecvInt64(&tmp64), IsTrue());
     EXPECT_THAT(tmp64, Eq(-1099511627776LL));
   };
   auto b = [](Comms* comms) {
     // Recv Uint64.
-    uint64 tmpu64;
+    uint64_t tmpu64;
     ASSERT_THAT(comms->RecvUint64(&tmpu64), IsTrue());
     EXPECT_THAT(tmpu64, Eq(1099511627776ULL));