diff --git a/ports/qemu/Makefile b/ports/qemu/Makefile
index b78281c916..5503c4b649 100644
--- a/ports/qemu/Makefile
+++ b/ports/qemu/Makefile
@@ -19,8 +19,12 @@ QSTR_DEFS = qstrdefsport.h
 MICROPY_ROM_TEXT_COMPRESSION ?= 1
 
 ifeq ($(QEMU_ARCH),arm)
+ifeq ($(BOARD),MICROBIT)
+FROZEN_MANIFEST ?= "freeze('test-frzmpy', ('frozen_const.py'))"
+else
 FROZEN_MANIFEST ?= "freeze('test-frzmpy')"
 endif
+endif
 ifeq ($(QEMU_ARCH),riscv32)
 FROZEN_MANIFEST ?= "freeze('test-frzmpy', ('frozen_const.py', 'frozen_viper.py', 'native_frozen_align.py'))"
 endif
diff --git a/ports/qemu/mpconfigport.h b/ports/qemu/mpconfigport.h
index f3dd8c3750..c81248ac3a 100644
--- a/ports/qemu/mpconfigport.h
+++ b/ports/qemu/mpconfigport.h
@@ -34,8 +34,10 @@
 #define MICROPY_EMIT_ARM            (1)
 #define MICROPY_EMIT_INLINE_THUMB   (1)
 #elif defined(__ARM_ARCH_ISA_THUMB)
+#if !defined(QEMU_SOC_NRF51)
 #define MICROPY_EMIT_THUMB          (1)
 #define MICROPY_EMIT_INLINE_THUMB   (1)
+#endif
 #define MICROPY_MAKE_POINTER_CALLABLE(p) ((void *)((mp_uint_t)(p) | 1))
 #elif defined(__riscv)
 #define MICROPY_EMIT_RV32           (1)