diff --git a/wadsrc/static/zscript/engine/maps.zs b/wadsrc/static/zscript/engine/maps.zs
index d6a8e6b905a..87546f7bdb9 100644
--- a/wadsrc/static/zscript/engine/maps.zs
+++ b/wadsrc/static/zscript/engine/maps.zs
@@ -5,13 +5,13 @@ struct Map_I32_I8 native
     native void Move(Map_I32_I8 other);
     native void Swap(Map_I32_I8 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native int Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") int GetIfExists(int key);
-    native version("4.11") int CheckValue(int key, out bool exists);
+    native version("4.11") int GetIfExists(int key) const;
+    native version("4.11") int CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, int value);
     native void InsertNew(int key);
@@ -37,13 +37,13 @@ struct Map_I32_I16 native
     native void Move(Map_I32_I16 other);
     native void Swap(Map_I32_I16 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native int Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") int GetIfExists(int key);
-    native version("4.11") int CheckValue(int key, out bool exists);
+    native version("4.11") int GetIfExists(int key) const;
+    native version("4.11") int CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, int value);
     native void InsertNew(int key);
@@ -69,13 +69,13 @@ struct Map_I32_I32 native
     native void Move(Map_I32_I32 other);
     native void Swap(Map_I32_I32 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native int Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") int GetIfExists(int key);
-    native version("4.11") int CheckValue(int key, out bool exists);
+    native version("4.11") int GetIfExists(int key) const;
+    native version("4.11") int CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, int value);
     native void InsertNew(int key);
@@ -101,13 +101,13 @@ struct Map_I32_F32 native
     native void Move(Map_I32_F32 other);
     native void Swap(Map_I32_F32 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native double Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") double GetIfExists(int key);
-    native version("4.11") double CheckValue(int key, out bool exists);
+    native version("4.11") double GetIfExists(int key) const;
+    native version("4.11") double CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, double value);
     native void InsertNew(int key);
@@ -133,13 +133,13 @@ struct Map_I32_F64 native
     native void Move(Map_I32_F64 other);
     native void Swap(Map_I32_F64 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native double Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") double GetIfExists(int key);
-    native version("4.11") double CheckValue(int key, out bool exists);
+    native version("4.11") double GetIfExists(int key) const;
+    native version("4.11") double CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, double value);
     native void InsertNew(int key);
@@ -165,13 +165,13 @@ struct Map_I32_Obj native
     native void Move(Map_I32_Obj other);
     native void Swap(Map_I32_Obj other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native Object Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") Object GetIfExists(int key);
-    native version("4.11") Object CheckValue(int key, out bool exists);
+    native version("4.11") Object GetIfExists(int key) const;
+    native version("4.11") Object CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, Object value);
     native void InsertNew(int key);
@@ -197,13 +197,13 @@ struct Map_I32_Ptr native
     native void Move(Map_I32_Ptr other);
     native void Swap(Map_I32_Ptr other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native voidptr Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") voidptr GetIfExists(int key);
-    native version("4.11") voidptr CheckValue(int key, out bool exists);
+    native version("4.11") voidptr GetIfExists(int key) const;
+    native version("4.11") voidptr CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, voidptr value);
     native void InsertNew(int key);
@@ -226,13 +226,13 @@ struct Map_I32_Str native
     native void Move(Map_I32_Str other);
     native void Swap(Map_I32_Str other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native String Get(int key);
-    native bool CheckKey(int key);
+    native bool CheckKey(int key) const;
     
-    native version("4.11") String GetIfExists(int key);
-    native version("4.11") String CheckValue(int key, out bool exists);
+    native version("4.11") String GetIfExists(int key) const;
+    native version("4.11") String CheckValue(int key, out bool exists) const;
     
     native void Insert(int key, String value);
     native void InsertNew(int key);
@@ -260,13 +260,13 @@ struct Map_Str_I8 native
     native void Move(Map_Str_I8 other);
     native void Swap(Map_Str_I8 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native int Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") int GetIfExists(String key);
-    native version("4.11") int CheckValue(String key, out bool exists);
+    native version("4.11") int GetIfExists(String key) const;
+    native version("4.11") int CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, int value);
     native void InsertNew(String key);
@@ -292,13 +292,13 @@ struct Map_Str_I16 native
     native void Move(Map_Str_I16 other);
     native void Swap(Map_Str_I16 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native int Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") int GetIfExists(String key);
-    native version("4.11") int CheckValue(String key, out bool exists);
+    native version("4.11") int GetIfExists(String key) const;
+    native version("4.11") int CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, int value);
     native void InsertNew(String key);
@@ -324,13 +324,13 @@ struct Map_Str_I32 native
     native void Move(Map_Str_I32 other);
     native void Swap(Map_Str_I32 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native int Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") int GetIfExists(String key);
-    native version("4.11") int CheckValue(String key, out bool exists);
+    native version("4.11") int GetIfExists(String key) const;
+    native version("4.11") int CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, int value);
     native void InsertNew(String key);
@@ -356,13 +356,13 @@ struct Map_Str_F32 native
     native void Move(Map_Str_F32 other);
     native void Swap(Map_Str_F32 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native double Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") double GetIfExists(String key);
-    native version("4.11") double CheckValue(String key, out bool exists);
+    native version("4.11") double GetIfExists(String key) const;
+    native version("4.11") double CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, double value);
     native void InsertNew(String key);
@@ -388,13 +388,13 @@ struct Map_Str_F64 native
     native void Move(Map_Str_F64 other);
     native void Swap(Map_Str_F64 other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native double Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") double GetIfExists(String key);
-    native version("4.11") double CheckValue(String key, out bool exists);
+    native version("4.11") double GetIfExists(String key) const;
+    native version("4.11") double CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, double value);
     native void InsertNew(String key);
@@ -420,13 +420,13 @@ struct Map_Str_Obj native
     native void Move(Map_Str_Obj other);
     native void Swap(Map_Str_Obj other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native Object Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") Object GetIfExists(String key);
-    native version("4.11") Object CheckValue(String key, out bool exists);
+    native version("4.11") Object GetIfExists(String key) const;
+    native version("4.11") Object CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, Object value);
     native void InsertNew(String key);
@@ -452,13 +452,13 @@ struct Map_Str_Ptr native
     native void Move(Map_Str_Ptr other);
     native void Swap(Map_Str_Ptr other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native voidptr Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") voidptr GetIfExists(String key);
-    native version("4.11") voidptr CheckValue(String key, out bool exists);
+    native version("4.11") voidptr GetIfExists(String key) const;
+    native version("4.11") voidptr CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, voidptr value);
     native void InsertNew(String key);
@@ -484,13 +484,13 @@ struct Map_Str_Str native
     native void Move(Map_Str_Str other);
     native void Swap(Map_Str_Str other);
     native void Clear();
-    native uint CountUsed();
+    native uint CountUsed() const;
 
     native String Get(String key);
-    native bool CheckKey(String key);
+    native bool CheckKey(String key) const;
     
-    native version("4.11") String GetIfExists(String key);
-    native version("4.11") String CheckValue(String key, out bool exists);
+    native version("4.11") String GetIfExists(String key) const;
+    native version("4.11") String CheckValue(String key, out bool exists) const;
     
     native void Insert(String key, String value);
     native void InsertNew(String key);