diff --git a/lib/cpp/src/thrift/server/TNonblockingServer.cpp b/lib/cpp/src/thrift/server/TNonblockingServer.cpp
index eea0427..26ffa68 100644
--- a/lib/cpp/src/thrift/server/TNonblockingServer.cpp
+++ b/lib/cpp/src/thrift/server/TNonblockingServer.cpp
@@ -492,7 +492,11 @@
 
   case SOCKET_RECV:
     // It is an error to be in this state if we already have all the data
-    assert(readBufferPos_ < readWant_);
+    if (!(readBufferPos_ < readWant_)) {
+      GlobalOutput.printf("TNonblockingServer: frame size too short");
+      close();
+      return;
+    }
 
     try {
       // Read from the socket