diff --git a/ports/rp2/mphalport.c b/ports/rp2/mphalport.c
index d3824d8f91..63ff76f5d9 100644
--- a/ports/rp2/mphalport.c
+++ b/ports/rp2/mphalport.c
@@ -204,3 +204,8 @@ void mp_hal_get_mac_ascii(int idx, size_t chr_off, size_t chr_len, char *dest) {
         *dest++ = hexchr[mac[chr_off >> 1] >> (4 * (1 - (chr_off & 1))) & 0xf];
     }
 }
+
+// Shouldn't be used, needed by cyw43-driver in debug build.
+uint32_t storage_read_blocks(uint8_t *dest, uint32_t block_num, uint32_t num_blocks) {
+    panic_unsupported();
+}