diff --git a/os/hal/ports/STM32/LLD/MACv1/hal_mac_lld.c b/os/hal/ports/STM32/LLD/MACv1/hal_mac_lld.c
index 5b8d5a8a6..820f93263 100644
--- a/os/hal/ports/STM32/LLD/MACv1/hal_mac_lld.c
+++ b/os/hal/ports/STM32/LLD/MACv1/hal_mac_lld.c
@@ -143,7 +143,7 @@ static void mii_find_phy(MACDriver *macp) {
   unsigned n = STM32_MAC_PHY_TIMEOUT;
  do {
 #endif
-    for (i = 0U; i < 31U; i++) {
+    for (i = 0U; i <= 31U; i++) {
       macp->phyaddr = i << 11U;
       ETH->MACMIIDR = (i << 6U) | MACMIIDR_CR;
       if ((mii_read(macp, MII_PHYSID1) == (BOARD_PHY_ID >> 16U)) &&
diff --git a/readme.txt b/readme.txt
index 10f6acce2..be12c6dac 100644
--- a/readme.txt
+++ b/readme.txt
@@ -143,6 +143,8 @@
 - EX:  Updated LSM303DLHC to 1.1.0 (backported to 18.2.1).
 - HAL: Fixed invalid checks in STM32F37x HAL related to SDADC (bug #974)
        (backported to 18.2.2 and 17.6.5).
+- HAL: Fixed mii_find_phy excludes PHY address 31 (bug #971)
+       (backported to 18.2.2 and 17.6.5).
 - HAL: Fixed option STM32_LSCOSEL not written in STM32L4 HAL (bug #970)
        (backported to 18.2.2 and 17.6.5).
 - HAL: Fixed invalid DFSDM1SEL option in STM32L4 HAL (bug #969)(backported