diff --git a/inc/core/MicroBitConfig.h b/inc/core/MicroBitConfig.h
index ccb8ed6..fe086ee 100644
--- a/inc/core/MicroBitConfig.h
+++ b/inc/core/MicroBitConfig.h
@@ -425,14 +425,14 @@ extern uint32_t __etext;
 // n.b. This also disables the user serial port 'uBit.serial'.
 // Set '1' to enable.
 #ifndef MICROBIT_DBG
-#define MICROBIT_DBG                            1
+#define MICROBIT_DBG                            0
 #endif
 
 // Enable this to receive diagnostic messages from the heap allocator via the USB serial interface.
 // n.b. This requires MICROBIT_DBG to be defined.
 // Set '1' to enable.
 #ifndef MICROBIT_HEAP_DBG
-#define MICROBIT_HEAP_DBG                       1
+#define MICROBIT_HEAP_DBG                       0
 #endif
 
 // Versioning options.