diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index e49a58c8..0deb3a1b 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
 - Sending invalid UTF-8 TEXT message should fail and close the connection (fix remaining autobahn test: 6.X UTF-8 Handling)
 - Fix failing unittest which was sending binary data in text mode with WebSocket::send to call properly call WebSocket::sendBinary instead.
 - Validate that the reason is proper utf-8. (fix autobahn test 7.5.1)
+- Validate close codes. Autobahn 7.9.*
 
 ## [5.1.5] - 2019-09-03
 
diff --git a/ixwebsocket/IXWebSocketCloseConstants.cpp b/ixwebsocket/IXWebSocketCloseConstants.cpp
index 6e9036e3..65accb1b 100644
--- a/ixwebsocket/IXWebSocketCloseConstants.cpp
+++ b/ixwebsocket/IXWebSocketCloseConstants.cpp
@@ -27,4 +27,5 @@ namespace ix
     const std::string WebSocketCloseConstants::kProtocolErrorCodeDataOpcodeOutOfSequence("Fragmentation: data message out of sequence");
     const std::string WebSocketCloseConstants::kProtocolErrorCodeContinuationOpCodeOutOfSequence("Fragmentation: continuation opcode out of sequence");
     const std::string WebSocketCloseConstants::kInvalidFramePayloadDataMessage("Invalid frame payload data");
+    const std::string WebSocketCloseConstants::kInvalidCloseCodeMessage("Invalid close code");
 }
diff --git a/ixwebsocket/IXWebSocketCloseConstants.h b/ixwebsocket/IXWebSocketCloseConstants.h
index 7a10405f..145777b9 100644
--- a/ixwebsocket/IXWebSocketCloseConstants.h
+++ b/ixwebsocket/IXWebSocketCloseConstants.h
@@ -32,5 +32,6 @@ namespace ix
         static const std::string kProtocolErrorCodeDataOpcodeOutOfSequence;
         static const std::string kProtocolErrorCodeContinuationOpCodeOutOfSequence;
         static const std::string kInvalidFramePayloadDataMessage;
+        static const std::string kInvalidCloseCodeMessage;
     };
 } // namespace ix
diff --git a/ixwebsocket/IXWebSocketTransport.cpp b/ixwebsocket/IXWebSocketTransport.cpp
index d5664dde..4c7cf492 100644
--- a/ixwebsocket/IXWebSocketTransport.cpp
+++ b/ixwebsocket/IXWebSocketTransport.cpp
@@ -684,6 +684,20 @@ namespace ix
                         code = WebSocketCloseConstants::kInvalidFramePayloadData;
                         reason = WebSocketCloseConstants::kInvalidFramePayloadDataMessage;
                     }
+
+                    // Validate close codes. Autobahn 7.9.*
+                    // 1014, 1015 are debattable. The firefox MSDN has a description for them
+                    if (code < 1000 || code == 1004 || code == 1006 ||
+                        (code > 1013 && code < 3000))
+                    {
+                        // build up an error message containing the bad error code
+                        std::stringstream ss;
+                        ss << WebSocketCloseConstants::kInvalidCloseCodeMessage
+                           << ": " << code;
+                        reason = ss.str();
+
+                        code = WebSocketCloseConstants::kProtocolErrorCode;
+                    }
                 }
                 else
                 {