diff --git a/libs/microbit/basic.cpp b/libs/microbit/basic.cpp
index ebfd5dc4..15a4a97d 100644
--- a/libs/microbit/basic.cpp
+++ b/libs/microbit/basic.cpp
@@ -58,7 +58,7 @@ namespace basic {
       int l = s.length();
       if (l == 0) {
         uBit.display.clear();
-        uBit.sleep(interval * 5);
+        fiber_sleep(interval * 5);
       } else if (l > 1) {
         uBit.display.scroll(s, interval);
       } else {
@@ -98,7 +98,7 @@ namespace basic {
     void forever_stub(void *a) {
       while (true) {
         runAction0((Action)a);
-        uBit.sleep(20);
+        fiber_sleep(20);
       }
     }
 
@@ -123,6 +123,6 @@ namespace basic {
     //% async block="pause (ms) %pause"
     //% blockId=device_pause icon="\uf110"
     void pause(int ms) {
-      uBit.sleep(ms);
+      fiber_sleep(ms);
     }
 }
diff --git a/libs/microbit/control.cpp b/libs/microbit/control.cpp
index 0e838567..f228eb98 100644
--- a/libs/microbit/control.cpp
+++ b/libs/microbit/control.cpp
@@ -132,7 +132,7 @@ namespace control {
     //% weight=30 async help=control/reset
     //% blockId="control_reset" block="reset"
     void reset() { 
-      uBit.reset(); 
+      microbit_reset();
     }
 
     /**
diff --git a/libs/microbit/core.cpp b/libs/microbit/core.cpp
index e9ec6f82..5179f490 100644
--- a/libs/microbit/core.cpp
+++ b/libs/microbit/core.cpp
@@ -1,6 +1,7 @@
 #include "ksbit.h"
 #include <limits.h>
 
+
 namespace String_ {
     //%
     StringData *charAt(StringData *s, int pos) {
@@ -127,13 +128,13 @@ namespace Math_ {
     //%
     int random(int max) {
       if (max == INT_MIN)
-        return -uBit.random(INT_MAX);
+        return -microbit_random(INT_MAX);
       else if (max < 0)
-        return -uBit.random(-max);
+        return -microbit_random(-max);
       else if (max == 0)
         return 0;
       else
-        return uBit.random(max);
+        return microbit_random(max);
     }
     
     //%
@@ -298,6 +299,6 @@ namespace pxtrt {
   //%
   void panic(int code)
   {
-    uBit.panic(code);
+    microbit_panic(code);
   }
 }
diff --git a/libs/microbit/input.cpp b/libs/microbit/input.cpp
index 09bf758a..600e3a8b 100644
--- a/libs/microbit/input.cpp
+++ b/libs/microbit/input.cpp
@@ -247,7 +247,7 @@ namespace input {
     //% help=input/running-time weight=50
     //% blockId=device_get_running_time block="running time (ms)" icon="\uf017"
     int runningTime() {
-        return uBit.systemTime();
+        return system_timer_current_time();
     }
 
     /**
diff --git a/libs/microbit/pins.cpp b/libs/microbit/pins.cpp
index b2e8b629..20023570 100644
--- a/libs/microbit/pins.cpp
+++ b/libs/microbit/pins.cpp
@@ -180,8 +180,9 @@ namespace pins {
       }
       
       if (ms > 0) {
-          uBit.sleep(ms);
+          fiber_sleep(ms);
           pitchPin->setAnalogValue(0);
+          // TODO why do we use wait_ms() here? it's a busy wait I think
           wait_ms(5);
       }
     }
diff --git a/package.json b/package.json
index 480bcb69..0be23132 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "pxt-microbit",
-  "version": "0.2.78",
+  "version": "0.2.79",
   "description": "BBC micro:bit target for PXT",
   "keywords": [
     "JavaScript",
@@ -29,6 +29,6 @@
     "typescript": "^1.8.7"
   },
   "dependencies": {
-    "pxt-core": "0.2.82"
+    "pxt-core": "0.2.83"
   }
 }