diff --git a/libs/core/control.cpp b/libs/core/control.cpp
index c8074f48e7..fe642c5efb 100644
--- a/libs/core/control.cpp
+++ b/libs/core/control.cpp
@@ -271,6 +271,9 @@ namespace control {
       microbit_reset();
     }
 
+    //%
+    void singleSimulator() { }
+
     /**
     * Blocks the current fiber for the given microseconds
     * @param micros number of micro-seconds to wait. eg: 4
diff --git a/libs/core/control.ts b/libs/core/control.ts
index 63bcb116ee..2fdc47cae6 100644
--- a/libs/core/control.ts
+++ b/libs/core/control.ts
@@ -16,12 +16,12 @@ namespace control {
     export function runInBackground(a: () => void) {
         control.inBackground(a);
     }
-
     /**
      * Allow only one simulator
      */
-    //% shim=TD_NOOP
-    export function singleSimulator(): void {
+    //% shim=pxt::singleSimulator
+    export function singleSimulator(msg: string) { 
+
     }
 
     /**
diff --git a/pxtarget.json b/pxtarget.json
index 5bf1984cf2..ee683c8213 100644
--- a/pxtarget.json
+++ b/pxtarget.json
@@ -180,7 +180,6 @@
         "dockerImage": "pext/yotta:gcc5"
     },
     "multiVariants": [
-        "mbdal",
         "mbcodal"
     ],
     "alwaysMultiVariant" : true,