diff --git a/custom_components/mikrotik_router/__init__.py b/custom_components/mikrotik_router/__init__.py
index 58c302b..d3c874e 100644
--- a/custom_components/mikrotik_router/__init__.py
+++ b/custom_components/mikrotik_router/__init__.py
@@ -78,7 +78,7 @@ async def async_setup_entry(hass, config_entry):
     device_registry = await hass.helpers.device_registry.async_get_registry()
     device_registry.async_get_or_create(
         config_entry_id=config_entry.entry_id,
-        connections={(DOMAIN, controller.data["routerboard"]["serial-number"])},
+        connections={(DOMAIN, f"{controller.data['routerboard']['serial-number']}")},
         manufacturer=controller.data["resource"]["platform"],
         model=controller.data["routerboard"]["model"],
         name=f"{config_entry.data[CONF_NAME]} {controller.data['routerboard']['model']}",
@@ -87,7 +87,7 @@ async def async_setup_entry(hass, config_entry):
         identifiers={
             DOMAIN,
             "serial-number",
-            controller.data["routerboard"]["serial-number"],
+            f"{controller.data['routerboard']['serial-number']}",
             "sensor",
             f"{config_entry.data[CONF_NAME]} {controller.data['routerboard']['model']}",
         },
diff --git a/custom_components/mikrotik_router/binary_sensor.py b/custom_components/mikrotik_router/binary_sensor.py
index 5f9fc7e..1cb4648 100644
--- a/custom_components/mikrotik_router/binary_sensor.py
+++ b/custom_components/mikrotik_router/binary_sensor.py
@@ -306,7 +306,9 @@ class MikrotikControllerBinarySensor(BinarySensorEntity):
             self._type[ATTR_GROUP] = self._ctrl.data["resource"]["board-name"]
 
         info = {
-            "connections": {(DOMAIN, self._ctrl.data["routerboard"]["serial-number"])},
+            "connections": {
+                (DOMAIN, f"{self._ctrl.data['routerboard']['serial-number']}")
+            },
             "manufacturer": self._ctrl.data["resource"]["platform"],
             "model": self._ctrl.data["resource"]["board-name"],
             "name": f"{self._inst} {self._type[ATTR_GROUP]}",
@@ -318,7 +320,7 @@ class MikrotikControllerBinarySensor(BinarySensorEntity):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "sensor",
                     f"{self._inst} {self._type[ATTR_GROUP]}",
                 )
@@ -418,7 +420,7 @@ class MikrotikControllerPPPSecretBinarySensor(MikrotikControllerBinarySensor):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "PPP",
                 )
diff --git a/custom_components/mikrotik_router/button.py b/custom_components/mikrotik_router/button.py
index 778b3b4..914717b 100644
--- a/custom_components/mikrotik_router/button.py
+++ b/custom_components/mikrotik_router/button.py
@@ -199,7 +199,7 @@ class MikrotikControllerScriptButton(MikrotikControllerButton):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "button",
                     "Scripts",
                 )
diff --git a/custom_components/mikrotik_router/sensor.py b/custom_components/mikrotik_router/sensor.py
index 7e4c3b3..eea7db6 100644
--- a/custom_components/mikrotik_router/sensor.py
+++ b/custom_components/mikrotik_router/sensor.py
@@ -463,7 +463,9 @@ class MikrotikControllerSensor(SensorEntity):
             self._type[ATTR_GROUP] = self._ctrl.data["resource"]["board-name"]
 
         info = {
-            "connections": {(DOMAIN, self._ctrl.data["routerboard"]["serial-number"])},
+            "connections": {
+                (DOMAIN, f"{self._ctrl.data['routerboard']['serial-number']}")
+            },
             "manufacturer": self._ctrl.data["resource"]["platform"],
             "model": self._ctrl.data["resource"]["board-name"],
             "name": f"{self._inst} {self._type[ATTR_GROUP]}",
@@ -475,7 +477,7 @@ class MikrotikControllerSensor(SensorEntity):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "sensor",
                     f"{self._inst} {self._type[ATTR_GROUP]}",
                 )
@@ -631,7 +633,7 @@ class MikrotikControllerEnvironmentSensor(MikrotikControllerSensor):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "sensor",
                     "Environment",
                 )
diff --git a/custom_components/mikrotik_router/switch.py b/custom_components/mikrotik_router/switch.py
index ed84927..c7de95e 100644
--- a/custom_components/mikrotik_router/switch.py
+++ b/custom_components/mikrotik_router/switch.py
@@ -510,7 +510,7 @@ class MikrotikControllerNATSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "NAT",
                 )
@@ -599,7 +599,7 @@ class MikrotikControllerMangleSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "Mangle",
                 )
@@ -688,7 +688,7 @@ class MikrotikControllerFilterSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "Filter",
                 )
@@ -774,7 +774,7 @@ class MikrotikControllerPPPSecretSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "PPP",
                 )
@@ -834,7 +834,7 @@ class MikrotikControllerQueueSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "Queue",
                 )
@@ -902,7 +902,7 @@ class MikrotikControllerKidcontrolSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "Kidcontrol",
                 )
@@ -977,7 +977,7 @@ class MikrotikControllerKidcontrolPauseSwitch(MikrotikControllerSwitch):
                 (
                     DOMAIN,
                     "serial-number",
-                    self._ctrl.data["routerboard"]["serial-number"],
+                    f"{self._ctrl.data['routerboard']['serial-number']}",
                     "switch",
                     "Kidcontrol",
                 )