diff --git a/source/ports/rs_port/src/cast.rs b/source/ports/rs_port/src/cast.rs
index 51574fdf1..61e4c3e8c 100644
--- a/source/ports/rs_port/src/cast.rs
+++ b/source/ports/rs_port/src/cast.rs
@@ -235,6 +235,6 @@ pub fn metacallobj_untyped_to_raw(ret: Box<dyn MetaCallValue>) -> Option<*mut c_
     None
 }
 
-pub fn metacall_implementer_to_traitobj(v: impl MetaCallValue) -> Box<dyn MetaCallValue> {
+pub fn metacall_box(v: impl MetaCallValue) -> Box<dyn MetaCallValue> {
     Box::new(v) as Box<dyn MetaCallValue>
 }
diff --git a/source/ports/rs_port/src/lib.rs b/source/ports/rs_port/src/lib.rs
index 0f1f282a0..3c7c9e94d 100644
--- a/source/ports/rs_port/src/lib.rs
+++ b/source/ports/rs_port/src/lib.rs
@@ -88,6 +88,7 @@ pub use types::*;
 #[doc(hidden)]
 mod init;
 
+pub use cast::metacall_box;
 pub use init::initialize;
 pub use init::is_initialized;
 
diff --git a/source/ports/rs_port/src/types/metacall_exception.rs b/source/ports/rs_port/src/types/metacall_exception.rs
index c3bf662cc..f753fce6c 100644
--- a/source/ports/rs_port/src/types/metacall_exception.rs
+++ b/source/ports/rs_port/src/types/metacall_exception.rs
@@ -180,7 +180,7 @@ impl MetaCallThrowable {
             Ok(mut value) => {
                 value.leak = true;
 
-                cast::metacall_implementer_to_traitobj(value)
+                cast::metacall_box(value)
             }
             Err(original) => original,
         }
diff --git a/source/ports/rs_port/src/types/metacall_value.rs b/source/ports/rs_port/src/types/metacall_value.rs
index 97a669567..bbc5870ff 100644
--- a/source/ports/rs_port/src/types/metacall_value.rs
+++ b/source/ports/rs_port/src/types/metacall_value.rs
@@ -429,3 +429,36 @@ impl MetaCallValue for MetaCallThrowable {
         self.into_raw()
     }
 }
+/// Just a Rust barrier made for easier polymorphism.
+impl MetaCallValue for Box<dyn MetaCallValue> {
+    fn get_metacall_id() -> metacall_value_id {
+        metacall_value_id::METACALL_INVALID
+    }
+    fn from_metacall_raw_leak(v: *mut c_void) -> Result<Self, Box<dyn MetaCallValue>> {
+        Ok(cast::raw_to_metacallobj_untyped_leak(v))
+    }
+    fn into_metacall_raw(self) -> *mut c_void {
+        match_metacall_value!(self, {
+            bool: bool => bool.into_metacall_raw(),
+            char: char => char.into_metacall_raw(),
+            num: i16 => num.into_metacall_raw(),
+            num: i32 => num.into_metacall_raw(),
+            num: i64 => num.into_metacall_raw(),
+            num: f32 => num.into_metacall_raw(),
+            num: f64 => num.into_metacall_raw(),
+            str: String => str.into_metacall_raw(),
+            buf: Vec<i8> => buf.into_metacall_raw(),
+            arr: Vec<Box<dyn MetaCallValue>> => arr.into_metacall_raw(),
+            map: HashMap<String, Box<dyn MetaCallValue>> => map.into_metacall_raw(),
+            ptr: MetaCallPointer => ptr.into_metacall_raw(),
+            fut: MetaCallFuture => fut.into_metacall_raw(),
+            fun: MetaCallFunction => fun.into_metacall_raw(),
+            null: MetaCallNull => null.into_metacall_raw(),
+            cls: MetaCallClass => cls.into_metacall_raw(),
+            obj: MetaCallObject => obj.into_metacall_raw(),
+            exc: MetaCallException => exc.into_metacall_raw(),
+            thr: MetaCallThrowable => thr.into_metacall_raw(),
+            _ => MetaCallNull().into_metacall_raw()
+        })
+    }
+}
diff --git a/source/ports/rs_port/tests/metacall_test.rs b/source/ports/rs_port/tests/metacall_test.rs
index ad6389262..9963240d8 100644
--- a/source/ports/rs_port/tests/metacall_test.rs
+++ b/source/ports/rs_port/tests/metacall_test.rs
@@ -81,27 +81,21 @@ fn test_float() {
 fn test_double() {
     generate_test::<f64>("test_double", 1.2345_f64);
 }
-// TODO
-// fn test_mixed_numbers() {
-//     let result = ::metacall::metacall::<i64>(
-//         "test_mixed_numbers",
-//         [
-//             Box::new(1 as i16) as Box<dyn MetaCallValue>,
-//             Box::new(2 as i32) as Box<dyn MetaCallValue>,
-//             Box::new(3 as i64) as Box<dyn MetaCallValue>,
-//         ],
-//     );
-
-//     // TODO
-//     // ::metacall::metacall::<i64>("test_mixed_numbers", [1_i16, 2_i32, 3_i64]);
-//     // ::metacall::metacall::<i64>("test_mixed_numbers", (1_i16, 2_i32, 3_i64));
-
-//     assert!(result.is_ok());
+fn test_mixed_numbers() {
+    let result = ::metacall::metacall::<i64>(
+        "test_mixed_numbers",
+        [
+            ::metacall::metacall_box(1 as i16),
+            ::metacall::metacall_box(2 as i32),
+            ::metacall::metacall_box(3 as i64),
+        ],
+    );
 
-//     if let Ok(ret) = result {
-//         assert_eq!(ret, 6_i64)
-//     }
-// }
+    assert!(result.is_ok());
+    if let Ok(ret) = result {
+        assert_eq!(ret, 6_i64)
+    }
+}
 fn test_string() {
     generate_test::<String>(
         "return_the_argument_py",
@@ -393,8 +387,7 @@ fn metacall() {
         test_int();
         test_long();
         test_short();
-        // TODO
-        // test_mixed_numbers();
+        test_mixed_numbers();
     }
     if load::from_single_file("node", js_test_file).is_ok() {
         test_exception();