diff --git a/source/funkin/modding/PolymodHandler.hx b/source/funkin/modding/PolymodHandler.hx
index 32be3c8e0..7f9fa24c5 100644
--- a/source/funkin/modding/PolymodHandler.hx
+++ b/source/funkin/modding/PolymodHandler.hx
@@ -211,6 +211,10 @@ class PolymodHandler
     Polymod.addImportAlias('flixel.math.FlxPoint', flixel.math.FlxPoint.FlxBasePoint);
 
     // Add blacklisting for prohibited classes and packages.
+
+    // `Sys`
+    Polymod.blacklistImport('Sys');
+
     // `polymod.*`
     for (cls in ClassMacro.listClassesInPackage('polymod'))
     {
@@ -218,6 +222,14 @@ class PolymodHandler
       var className:String = Type.getClassName(cls);
       Polymod.blacklistImport(className);
     }
+
+    // `sys.*`
+    for (cls in ClassMacro.listClassesInPackage('sys'))
+    {
+      if (cls == null) continue;
+      var className:String = Type.getClassName(cls);
+      Polymod.blacklistImport(className);
+    }
   }
 
   static function buildParseRules():polymod.format.ParseRules