diff --git a/common/rfb/SConnection.cxx b/common/rfb/SConnection.cxx
index 02865af183..f70d21dced 100644
--- a/common/rfb/SConnection.cxx
+++ b/common/rfb/SConnection.cxx
@@ -23,6 +23,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <assert.h>
 #include <rfb/Exception.h>
 #include <rfb/Security.h>
 #include <rfb/clipboardTypes.h>
@@ -59,7 +60,7 @@ SConnection::SConnection()
     is(0), os(0), reader_(0), writer_(0), ssecurity(0),
     authFailureTimer(this, &SConnection::handleAuthFailureTimeout),
     state_(RFBSTATE_UNINITIALISED), preferredEncoding(encodingRaw),
-    clientClipboard(NULL), hasLocalClipboard(false),
+    accessRights(0x0000), clientClipboard(NULL), hasLocalClipboard(false),
     unsolicitedClipboardAttempt(false)
 {
   defaultMajorVersion = 3;
@@ -346,6 +347,8 @@ void SConnection::setAccessRights(AccessRights ar)
 
 bool SConnection::accessCheck(AccessRights ar) const
 {
+  assert(state_ >= RFBSTATE_QUERYING);
+
   return (accessRights & ar) == ar;
 }