diff --git a/nimble/controller/src/ble_ll_ctrl.c b/nimble/controller/src/ble_ll_ctrl.c
index 60306fd42..d55245e5a 100644
--- a/nimble/controller/src/ble_ll_ctrl.c
+++ b/nimble/controller/src/ble_ll_ctrl.c
@@ -686,11 +686,18 @@ ble_ll_ctrl_phy_update_ind_make(struct ble_ll_conn_sm *connsm, uint8_t *dptr,
     uint8_t tx_phys;
     uint8_t rx_phys;
     uint16_t instant;
+    uint8_t is_slave_sym = 0;
 
     /* Get preferences from PDU */
     tx_phys = dptr[0];
     rx_phys = dptr[1];
 
+    /* If we are master, check if slave requested symmetric PHY */
+    if (connsm->conn_role == BLE_LL_CONN_ROLE_MASTER) {
+        is_slave_sym = tx_phys == rx_phys;
+        is_slave_sym &= __builtin_popcount(tx_phys) == 1;
+    }
+
     /* Get m_to_s and s_to_m masks */
     if (slave_req) {
         m_to_s = connsm->phy_data.host_pref_tx_phys_mask & rx_phys;
@@ -711,6 +718,18 @@ ble_ll_ctrl_phy_update_ind_make(struct ble_ll_conn_sm *connsm, uint8_t *dptr,
         s_to_m = 0;
     }
 
+    /*
+     * Core 5.0, Vol 6, PartB, 5.1.10
+     *     If the slave specified a single PHY in both the TX_PHYS and RX_PHYS
+     *     fields and both fields are the same, the master shall either select
+     *     the PHY specified by the slave for both directions or shall leave
+     *     both directions unchanged.
+     */
+    if (is_slave_sym && (s_to_m != m_to_s)) {
+        s_to_m = 0;
+        m_to_s = 0;
+    }
+
     /* At this point, m_to_s and s_to_m are not masks; they are numeric */
 
     /*