diff --git a/ports/espressif/common-hal/_bleio/Adapter.c b/ports/espressif/common-hal/_bleio/Adapter.c
index 364a9dd5433f4..21cdd88b1dbcb 100644
--- a/ports/espressif/common-hal/_bleio/Adapter.c
+++ b/ports/espressif/common-hal/_bleio/Adapter.c
@@ -528,7 +528,6 @@ static int _advertising_event(struct ble_gap_event *event, void *self_in) {
             #endif
             break;
     }
-    background_callback_add_core(&bleio_background_callback);
     return 0;
 }
 
@@ -559,7 +558,13 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
         return rc;
     }
 
-    bool high_duty_directed = directed_to != NULL && interval <= 3.5 && timeout <= 1.3;
+    bool high_duty_directed = directed_to != NULL && interval <= 3.5 && timeout <= 1; // Really 1.3, but it's an int
+
+    uint32_t timeout_ms = timeout * 1000;
+    if (timeout_ms == 0) {
+        timeout_ms = BLE_HS_FOREVER;
+    }
+
 
     #if MYNEWT_VAL(BLE_EXT_ADV)
     bool extended = advertising_data_len > BLE_ADV_LEGACY_DATA_MAX_LEN ||
@@ -621,7 +626,7 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
         }
     }
 
-    rc = ble_gap_ext_adv_start(0, timeout / 10, 0);
+    rc = ble_gap_ext_adv_start(0, timeout_ms, 0);
     #else
     uint8_t conn_mode = connectable ? BLE_GAP_CONN_MODE_UND : BLE_GAP_CONN_MODE_NON;
     if (directed_to != NULL) {
@@ -650,7 +655,7 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
         }
     }
     rc = ble_gap_adv_start(own_addr_type, directed_to != NULL ? &peer: NULL,
-        timeout / 10,
+        timeout_ms,
         &adv_params,
         _advertising_event, self);
     #endif
@@ -694,11 +699,9 @@ void common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self, bool
         mp_raise_NotImplementedError(NULL);
     }
 
-    if (!timeout) {
-        timeout = BLE_HS_FOREVER;
-    } else if (timeout > INT32_MAX) {
+    if ((uint64_t)timeout * 1000ll >= BLE_HS_FOREVER) {
         mp_raise_bleio_BluetoothError(MP_ERROR_TEXT("Timeout is too long: Maximum timeout length is %d seconds"),
-            INT32_MAX / 1000);
+            BLE_HS_FOREVER / 1000 - 1);
     }
 
     CHECK_NIMBLE_ERROR(_common_hal_bleio_adapter_start_advertising(self, connectable, anonymous, timeout, interval,
diff --git a/ports/nordic/common-hal/_bleio/Adapter.c b/ports/nordic/common-hal/_bleio/Adapter.c
index 82d56b9c1b811..46db2ac488c59 100644
--- a/ports/nordic/common-hal/_bleio/Adapter.c
+++ b/ports/nordic/common-hal/_bleio/Adapter.c
@@ -742,6 +742,13 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
         common_hal_bleio_adapter_stop_advertising(self);
     }
 
+    // A zero timeout means unlimited. Do the checking here
+    // rather than in common_hal_bleio_adapter_start_advertising(), because
+    // _common_hal_bleio_adapter_start_advertising() is called for BLE workflow with
+    // a zero (unlimited) timeout.
+    if (timeout == 0) {
+        timeout = BLE_GAP_ADV_TIMEOUT_GENERAL_UNLIMITED;
+    }
     uint32_t err_code;
     bool extended = advertising_data_len > BLE_GAP_ADV_SET_DATA_SIZE_MAX ||
         scan_response_data_len > BLE_GAP_ADV_SET_DATA_SIZE_MAX;
@@ -871,15 +878,11 @@ void common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self, bool
     // Anonymous mode requires a timeout so that we don't continue to broadcast
     // the same data while cycling the MAC address -- otherwise, what's the
     // point of randomizing the MAC address?
-    if (!timeout) {
-        if (anonymous) {
-            // The Nordic macro is in units of 10ms. Convert to seconds.
-            uint32_t adv_timeout_max_secs = UNITS_TO_SEC(BLE_GAP_ADV_TIMEOUT_LIMITED_MAX, UNIT_10_MS);
-            uint32_t rotate_timeout_max_secs = BLE_GAP_DEFAULT_PRIVATE_ADDR_CYCLE_INTERVAL_S;
-            timeout = MIN(adv_timeout_max_secs, rotate_timeout_max_secs);
-        } else {
-            timeout = BLE_GAP_ADV_TIMEOUT_GENERAL_UNLIMITED;
-        }
+    if (anonymous) {
+        // The Nordic macro is in units of 10ms. Convert to seconds.
+        uint32_t adv_timeout_max_secs = UNITS_TO_SEC(BLE_GAP_ADV_TIMEOUT_LIMITED_MAX, UNIT_10_MS);
+        uint32_t rotate_timeout_max_secs = BLE_GAP_DEFAULT_PRIVATE_ADDR_CYCLE_INTERVAL_S;
+        timeout = MIN(adv_timeout_max_secs, rotate_timeout_max_secs);
     } else {
         if (SEC_TO_UNITS(timeout, UNIT_10_MS) > BLE_GAP_ADV_TIMEOUT_LIMITED_MAX) {
             mp_raise_bleio_BluetoothError(MP_ERROR_TEXT("Timeout is too long: Maximum timeout length is %d seconds"),
diff --git a/supervisor/shared/bluetooth/bluetooth.c b/supervisor/shared/bluetooth/bluetooth.c
index 48b186bbdf12d..68b43871ce161 100644
--- a/supervisor/shared/bluetooth/bluetooth.c
+++ b/supervisor/shared/bluetooth/bluetooth.c
@@ -132,8 +132,8 @@ static void supervisor_bluetooth_start_advertising(void) {
         return;
     }
     #endif
-    uint32_t timeout = 0;
-    float interval = 0.1f;
+    const uint32_t timeout = 0;  // 0 means advertise forever.
+    const float interval = 0.1f;
     int tx_power = 0;
     const uint8_t *adv = private_advertising_data;
     size_t adv_len = sizeof(private_advertising_data);