diff --git a/ports/nrf/mpconfigport.h b/ports/nrf/mpconfigport.h
index 61729f6d0a..cfb7187b7b 100644
--- a/ports/nrf/mpconfigport.h
+++ b/ports/nrf/mpconfigport.h
@@ -55,6 +55,9 @@
 #else
 #define MICROPY_FLOAT_IMPL          (MICROPY_FLOAT_IMPL_FLOAT)
 #endif
+#if NRF51
+#define MICROPY_ALLOC_GC_STACK_SIZE (32)
+#endif
 
 #define MICROPY_OPT_COMPUTED_GOTO   (0)
 #define MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE (0)