diff --git a/quic/api/test/QuicTransportBaseTest.cpp b/quic/api/test/QuicTransportBaseTest.cpp
index 3e9d3b619..63d424de5 100644
--- a/quic/api/test/QuicTransportBaseTest.cpp
+++ b/quic/api/test/QuicTransportBaseTest.cpp
@@ -538,7 +538,10 @@ class TestQuicTransport
   }
 
   void enableDatagram() {
-    conn_->datagramState.maxReadFrameSize = 65535;
+    // Note: the RFC says to use 65535 to enable the datagram extension.
+    // We are using +1 in tests to make sure that we avoid representing this
+    // value with an uint16
+    conn_->datagramState.maxReadFrameSize = 65536;
     conn_->datagramState.maxReadBufferSize = 10;
   }
 
diff --git a/quic/state/StateData.h b/quic/state/StateData.h
index 851f201ec..b53456086 100644
--- a/quic/state/StateData.h
+++ b/quic/state/StateData.h
@@ -695,8 +695,8 @@ struct QuicConnectionStateBase : public folly::DelayedDestruction {
   uint64_t numProbesWritableBytesLimited{0};
 
   struct DatagramState {
-    uint16_t maxReadFrameSize{kDefaultMaxDatagramFrameSize};
-    uint16_t maxWriteFrameSize{kDefaultMaxDatagramFrameSize};
+    uint32_t maxReadFrameSize{kDefaultMaxDatagramFrameSize};
+    uint32_t maxWriteFrameSize{kDefaultMaxDatagramFrameSize};
     uint32_t maxReadBufferSize{kDefaultMaxDatagramsBuffered};
     uint32_t maxWriteBufferSize{kDefaultMaxDatagramsBuffered};
     // Buffers Incoming Datagrams