diff --git a/Resources/Scripts/oolite-constrictor-hunt-mission.js b/Resources/Scripts/oolite-constrictor-hunt-mission.js
index 0fd96616..eb408c77 100644
--- a/Resources/Scripts/oolite-constrictor-hunt-mission.js
+++ b/Resources/Scripts/oolite-constrictor-hunt-mission.js
@@ -109,7 +109,7 @@ this.missionOffers = function ()
 		if (galaxyNumber < 2 && !missionVariables.conhunt && player.score > 255)
 		{
 			// there are no options to deal with, we don't need a callback function.
-			mission.runScreen({titleKey:"constrictor_hunt_title", messageKey:"constrictor_hunt_brief1", model: "constrictor"}, null);
+			mission.runScreen({titleKey:"constrictor_hunt_title", messageKey:"constrictor_hunt_brief1", model: "constrictor"});
 			if (galaxyNumber === 0)
 			{
 				mission.addMessageTextKey("constrictor_hunt_brief1a"); // galaxy = 0
@@ -124,7 +124,7 @@ this.missionOffers = function ()
 		}
 		if (missionVariables.conhunt === "CONSTRICTOR_DESTROYED")  // Variable is set by the ship script
 		{
-			mission.runScreen({titleKey:"constrictor_hunt_title", messageKey:"constrictor_hunt_debrief", model: "constrictor"}, null);
+			mission.runScreen({titleKey:"constrictor_hunt_title", messageKey:"constrictor_hunt_debrief", model: "constrictor"});
 			player.credits += 5000;
 			player.bounty = 0;	  // legal status
 			player.score += 256;  // ship kills
diff --git a/Resources/Scripts/oolite-nova-mission.js b/Resources/Scripts/oolite-nova-mission.js
index 1a0e1576..d6065515 100644
--- a/Resources/Scripts/oolite-nova-mission.js
+++ b/Resources/Scripts/oolite-nova-mission.js
@@ -57,26 +57,26 @@ this.missionOffers = function ()
 			if (missionVariables.nova === "NOVA_ESCAPED_SYSTEM")
 			{
 				player.ship.removeAllCargo();
-				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_hero", background:"solar.png"}, null);
+				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_hero", background:"solar.png"});
 				player.ship.manifest["Gem-Stones"] += 100;
 				this.endTheMission();
 			}
 			else if (missionVariables.nova === "NOVA_ESCAPE_POD")
 			{
 				player.ship.removeAllCargo();  // can only be done while docked.
-				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_disappointed", background:"solar.png"}, null);
+				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_disappointed", background:"solar.png"});
 				this.endTheMission();
 			}
 			else if (missionVariables.nova === "NOVA_ESCAPE_OTHER")
 			{
-				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_ignored", background:"solar.png"}, null);
+				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_ignored", background:"solar.png"});
 				this.endTheMission();
 			}
 			else if (missionVariables.nova === "NOVA_ESCAPE_COWARD" && !system.sun.isGoingNova && !system.sun.hasGoneNova)
 			{
 				player.decreaseContractReputation();
 				player.decreasePassengerReputation();
-				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_disappointed", background:"solar.png"}, null);
+				mission.runScreen({titleKey:"oolite_nova_title", messageKey:"oolite_nova_disappointed", background:"solar.png"});
 				this.endTheMission();
 			}
 		}
diff --git a/Resources/Scripts/oolite-thargoid-plans-mission.js b/Resources/Scripts/oolite-thargoid-plans-mission.js
index d4405b56..70af019f 100644
--- a/Resources/Scripts/oolite-thargoid-plans-mission.js
+++ b/Resources/Scripts/oolite-thargoid-plans-mission.js
@@ -49,7 +49,7 @@ this.missionOffers = function ()
 				player.score > 1280 &&
 				system.ID !== 83)
 			{
-				mission.runScreen({titleKey:"thargoid_plans_title", messageKey:"thargoid_plans_brief1"}, null);
+				mission.runScreen({titleKey:"thargoid_plans_title", messageKey:"thargoid_plans_brief1"});
 				missionVariables.thargplans = "PRELUDE";
 				mission.setInstructionsKey("thargoid_plans_info1");
 				mission.markSystem(83);
@@ -58,7 +58,7 @@ this.missionOffers = function ()
 				system.ID === 83)
 			{
 				mission.unmarkSystem(83);
-				mission.runScreen({titleKey:"thargoid_plans_title", messageKey:"thargoid_plans_brief2", model: "thargoid"}, null);
+				mission.runScreen({titleKey:"thargoid_plans_title", messageKey:"thargoid_plans_brief2", model: "thargoid"});
 				missionVariables.thargplans = "RUNNING";
 				mission.setInstructionsKey("thargoid_plans_info2");
 				mission.markSystem(36);
@@ -66,7 +66,7 @@ this.missionOffers = function ()
 			else if (missionVariables.thargplans === "RUNNING" &&
 					 system.ID === 36)
 			{
-				mission.runScreen({titleKey:"thargoid_plans_title", messageKey:"thargoid_plans_debrief", model: "thargoid"}, null);
+				mission.runScreen({titleKey:"thargoid_plans_title", messageKey:"thargoid_plans_debrief", model: "thargoid"});
 				player.score += 256; // ship kills
 				mission.setInstructions(null);  // reset the mission briefing
 				missionVariables.thargplans = "MISSION_COMPLETE";
diff --git a/src/Core/Scripting/OOJSMission.m b/src/Core/Scripting/OOJSMission.m
index 6c080ded..2f205393 100644
--- a/src/Core/Scripting/OOJSMission.m
+++ b/src/Core/Scripting/OOJSMission.m
@@ -402,9 +402,8 @@ static JSBool MissionRunScreen(JSContext *context, JSObject *this, uintN argc, j
 	if (argc>0) {
 		if (!JSVAL_IS_NULL(argv[0]) && !JSVAL_IS_VOID(argv[0]) && !JSVAL_IS_OBJECT(argv[0]))
 		{
-			OOReportJSBadArguments(context, nil, @"Mission.runScreen", 1, argv, @"Invalid argument", @"object");
-			*outResult = BOOLToJSVal(NO);
-			return YES;
+			OOReportJSBadArguments(context, @"Mission", @"runScreen", 1, argv, @"Invalid argument", @"object");
+			return NO;
 		}
 		
 		if (!JSVAL_IS_NULL(argv[0]) && !JSVAL_IS_VOID(argv[0]) && JSVAL_IS_OBJECT(argv[0])) params = JSVAL_TO_OBJECT(argv[0]);
@@ -413,9 +412,8 @@ static JSBool MissionRunScreen(JSContext *context, JSObject *this, uintN argc, j
 	if (argc > 1) function = argv[1];
 	if (!JSVAL_IS_OBJECT(function) || (!JSVAL_IS_NULL(function) && !JS_ObjectIsFunction(context, JSVAL_TO_OBJECT(function))))
 	{
-		OOReportJSBadArguments(context, nil, @"Mission.runScreen", 1, argv + 1, @"Invalid argument", @"function");
-		*outResult = BOOLToJSVal(NO);
-		return YES;
+		OOReportJSBadArguments(context, @"Mission", @"runScreen", 1, argv + 1, @"Invalid argument", @"function");
+		return NO;
 	}
 	
 	str=@"title";