diff --git a/CHANGELOG b/CHANGELOG
index be7c6d6a1..5f740f2fc 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -8,6 +8,11 @@ o Reformat Nmap COPYING file (e.g. remove C comment markers, reduce
   when presented by the Windows executable (NSIS) installer.  Thanks
   to Jah for the patch (which was modified slightly by Fyodor).
 
+o Changed the NSE function nmap.set_port_state() so that it checks to
+  see if the requested port is already in the requested state.  This
+  prevents "Duplicate port" messages during the script scan and the
+  inaccurate "script-set" state reason. [Kris]
+
 o Updated ripeQuery.nse to not print extraneous whitespace. [Kris]
 
 Nmap 4.60
diff --git a/nse_nmaplib.cc b/nse_nmaplib.cc
index 0bd3f8cb7..a9543be6a 100644
--- a/nse_nmaplib.cc
+++ b/nse_nmaplib.cc
@@ -371,12 +371,16 @@ static int l_set_port_state(lua_State* l, Target* target, Port* port) {
 		case 'o':
 			if (strcmp(state, "open")) 
 				luaL_argerror (l, 4, "Invalid port state.");
+			if (port->state == PORT_OPEN)
+				goto noset;
 			plist->addPort(port->portno, port->proto, NULL, PORT_OPEN);
 			port->state = PORT_OPEN;
 			break;
 		case 'c':
 			if (strcmp(state, "closed"))
 				luaL_argerror (l, 4, "Invalid port state.");
+			if (port->state == PORT_CLOSED)
+				goto noset;
 			plist->addPort(port->portno, port->proto, NULL, PORT_CLOSED);
 			port->state = PORT_CLOSED;
 			break;
@@ -386,6 +390,7 @@ static int l_set_port_state(lua_State* l, Target* target, Port* port) {
 
 	port->reason.reason_id = ER_SCRIPT;
 
+noset:
 	free(state);
 	return 0;
 }