diff --git a/src/script/api/script_list.cpp b/src/script/api/script_list.cpp
--- a/src/script/api/script_list.cpp
+++ b/src/script/api/script_list.cpp
@@ -11,6 +11,7 @@
 
 #include "../../stdafx.h"
 #include "script_list.hpp"
+#include "script_controller.hpp"
 #include "../../debug.h"
 #include "../../script/squirrel.hpp"
 
@@ -905,6 +906,16 @@ SQInteger ScriptList::Valuate(HSQUIRRELV
 			}
 		}
 
+		/* Kill the script when the valuator call takes way too long.
+		 * Triggered by nesting valuators, which then take billions of iterations. */
+		if (ScriptController::GetOpsTillSuspend() < -1000000) {
+			/* See below for explanation. The extra pop is the return value. */
+			sq_pop(vm, nparam + 4);
+
+			ScriptObject::SetAllowDoCommand(backup_allow);
+			return sq_throwerror(vm, "excessive CPU usage in valuator function");
+		}
+
 		/* Was something changed? */
 		if (previous_modification_count != this->modifications) {
 			/* See below for explanation. The extra pop is the return value. */