diff --git a/libs/core/_locales/core-jsdoc-strings.json b/libs/core/_locales/core-jsdoc-strings.json
index 446c44aab9c..625b9c00008 100644
--- a/libs/core/_locales/core-jsdoc-strings.json
+++ b/libs/core/_locales/core-jsdoc-strings.json
@@ -329,6 +329,7 @@
   "control.runtimeWarning": "Display warning in the simulator.",
   "control.setDebugFlags": "Set flags used when connecting an external debugger.",
   "control.simmessages.onReceived": "Registers the handler for a message on a given channel",
+  "control.singleSimulator": "Allow only one simulator",
   "control.waitForEvent": "Blocks the calling thread until the specified event is raised.",
   "control.waitMicros": "Blocks the current fiber for the given microseconds",
   "control.waitMicros|param|micros": "number of micro-seconds to wait. eg: 4",
diff --git a/libs/core/control.cpp b/libs/core/control.cpp
index c8074f48e75..031c37e7b92 100644
--- a/libs/core/control.cpp
+++ b/libs/core/control.cpp
@@ -271,6 +271,12 @@ 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 83b3a98718b..57d6f7a1c22 100644
--- a/libs/core/control.ts
+++ b/libs/core/control.ts
@@ -16,6 +16,14 @@ namespace control {
     export function runInBackground(a: () => void) {
         control.inBackground(a);
     }
+    
+    /**
+     * Allow only one simulator
+     */
+    //% shim=control::singleSimulator
+    export function singleSimulator() { 
+
+    }
 
     /**
      * Returns the value of a C++ runtime constant
diff --git a/package.json b/package.json
index 9f981731bbe..269533244ad 100644
--- a/package.json
+++ b/package.json
@@ -32,7 +32,7 @@
         "docs/static/icons/favicon.ico"
     ],
     "devDependencies": {
-        "@types/dom-mediacapture-record": "^1.0.16",
+        "@types/dom-mediacapture-record": "1.0.20",
         "@types/marked": "0.3.0",
         "@types/node": "8.10.66",
         "@types/react": "16.4.7",