diff --git a/include/net/mqtt.h b/include/net/mqtt.h
index feae487bcce..e1ada204faf 100644
--- a/include/net/mqtt.h
+++ b/include/net/mqtt.h
@@ -27,6 +27,7 @@
 #include <zephyr.h>
 #include <zephyr/types.h>
 #include <net/tls_credentials.h>
+#include <misc/mutex.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -404,7 +405,7 @@ struct mqtt_transport {
 /** @brief MQTT internal state. */
 struct mqtt_internal {
 	/** Internal. Mutex to protect access to the client instance. */
-	struct k_mutex mutex;
+	struct sys_mutex mutex;
 
 	/** Internal. Wall clock value (in milliseconds) of the last activity
 	 *  that occurred. Needed for periodic PING.
diff --git a/subsys/net/lib/mqtt/mqtt_os.h b/subsys/net/lib/mqtt/mqtt_os.h
index 708a9a4967d..31c84f10fc0 100644
--- a/subsys/net/lib/mqtt/mqtt_os.h
+++ b/subsys/net/lib/mqtt/mqtt_os.h
@@ -20,6 +20,7 @@
 
 #include <stddef.h>
 #include <kernel.h>
+#include <misc/mutex.h>
 
 #include <net/net_core.h>
 
@@ -41,7 +42,7 @@ extern "C" {
  */
 static inline void mqtt_mutex_init(struct mqtt_client *client)
 {
-	k_mutex_init(&client->internal.mutex);
+	sys_mutex_init(&client->internal.mutex);
 }
 
 /**@brief Acquire lock on the module specific mutex, if any.
@@ -51,14 +52,20 @@ static inline void mqtt_mutex_init(struct mqtt_client *client)
  */
 static inline void mqtt_mutex_lock(struct mqtt_client *client)
 {
-	(void)k_mutex_lock(&client->internal.mutex, K_FOREVER);
+	int ret = sys_mutex_lock(&client->internal.mutex, K_FOREVER);
+
+	__ASSERT(ret == 0, "sys_mutex_lock failed with %d", ret);
+	(void)ret;
 }
 
 /**@brief Release the lock on the module specific mutex, if any.
  */
 static inline void mqtt_mutex_unlock(struct mqtt_client *client)
 {
-	k_mutex_unlock(&client->internal.mutex);
+	int ret = sys_mutex_unlock(&client->internal.mutex);
+
+	__ASSERT(ret == 0, "sys_mutex_unlock failed with %d", ret);
+	(void)ret;
 }
 
 /**@brief Method to get the sys tick or a wall clock in millisecond resolution.