diff --git a/quic/QuicConstants.h b/quic/QuicConstants.h
index 9aa53f095..59570396b 100644
--- a/quic/QuicConstants.h
+++ b/quic/QuicConstants.h
@@ -159,6 +159,7 @@ enum class LocalErrorCode : uint32_t {
   INVALID_OPERATION = 0x40000017,
   STREAM_LIMIT_EXCEEDED = 0x40000018,
   CONNECTION_ABANDONED = 0x40000019,
+  CALLBACK_ALREADY_INSTALLED = 0x4000001A,
 };
 
 using QuicErrorCode =
diff --git a/quic/QuicException.cpp b/quic/QuicException.cpp
index de53e40c1..c8979de31 100644
--- a/quic/QuicException.cpp
+++ b/quic/QuicException.cpp
@@ -84,6 +84,8 @@ std::string toString(LocalErrorCode code) {
       return "New version negotiatied";
     case LocalErrorCode::INVALID_WRITE_CALLBACK:
       return "Invalid write callback";
+    case LocalErrorCode::CALLBACK_ALREADY_INSTALLED:
+      return "Callback already installed";
     case LocalErrorCode::TLS_HANDSHAKE_FAILED:
       return "TLS handshake failed";
     case LocalErrorCode::APP_ERROR:
diff --git a/quic/api/QuicTransportBase.cpp b/quic/api/QuicTransportBase.cpp
index e66a3e676..6b10de62d 100644
--- a/quic/api/QuicTransportBase.cpp
+++ b/quic/api/QuicTransportBase.cpp
@@ -1636,10 +1636,19 @@ QuicTransportBase::notifyPendingWriteOnStream(StreamId id, WriteCallback* wcb) {
   if (!qStream->writable()) {
     return folly::makeUnexpected(LocalErrorCode::STREAM_CLOSED);
   }
+
+  if (wcb == nullptr) {
+    return folly::makeUnexpected(LocalErrorCode::INVALID_WRITE_CALLBACK);
+  }
   // Add the callback to the pending write callbacks so that if we are closed
   // while we are scheduled in the loop, the close will error out the callbacks.
-  if (!pendingWriteCallbacks_.emplace(id, wcb).second) {
-    return folly::makeUnexpected(LocalErrorCode::INVALID_WRITE_CALLBACK);
+  auto wcbEmplaceResult = pendingWriteCallbacks_.emplace(id, wcb);
+  if (!wcbEmplaceResult.second) {
+    if ((wcbEmplaceResult.first)->second != wcb) {
+      return folly::makeUnexpected(LocalErrorCode::INVALID_WRITE_CALLBACK);
+    } else {
+      return folly::makeUnexpected(LocalErrorCode::CALLBACK_ALREADY_INSTALLED);
+    }
   }
   runOnEvbAsync([id](auto self) {
     auto wcbIt = self->pendingWriteCallbacks_.find(id);
diff --git a/quic/api/test/QuicTransportBaseTest.cpp b/quic/api/test/QuicTransportBaseTest.cpp
index 3768fd667..8213efd97 100644
--- a/quic/api/test/QuicTransportBaseTest.cpp
+++ b/quic/api/test/QuicTransportBaseTest.cpp
@@ -1214,6 +1214,17 @@ TEST_P(QuicTransportImplTestClose, TestNotifyPendingConnWriteOnCloseWithError) {
   evb->loopOnce();
 }
 
+TEST_F(QuicTransportImplTest, TestNotifyPendingWriteWithActiveCallback) {
+  auto stream = transport->createBidirectionalStream().value();
+  MockWriteCallback wcb;
+  EXPECT_CALL(wcb, onStreamWriteReady(stream, _));
+  auto ok1 = transport->notifyPendingWriteOnStream(stream, &wcb);
+  EXPECT_TRUE(ok1.hasValue());
+  auto ok2 = transport->notifyPendingWriteOnStream(stream, &wcb);
+  EXPECT_EQ(ok2.error(), quic::LocalErrorCode::CALLBACK_ALREADY_INSTALLED);
+  evb->loopOnce();
+}
+
 TEST_F(QuicTransportImplTest, TestNotifyPendingWriteOnCloseWithoutError) {
   auto stream = transport->createBidirectionalStream().value();
   MockWriteCallback wcb;