diff --git a/py/malloc.c b/py/malloc.c
index ea1d4c4b9e..818a3e57a9 100644
--- a/py/malloc.c
+++ b/py/malloc.c
@@ -39,6 +39,9 @@
 #endif
 
 #if MICROPY_MEM_STATS
+#if !MICROPY_MALLOC_USES_ALLOCATED_SIZE
+#error MICROPY_MEM_STATS requires MICROPY_MALLOC_USES_ALLOCATED_SIZE
+#endif
 #define UPDATE_PEAK() { if (MP_STATE_MEM(current_bytes_allocated) > MP_STATE_MEM(peak_bytes_allocated)) MP_STATE_MEM(peak_bytes_allocated) = MP_STATE_MEM(current_bytes_allocated); }
 #endif