diff --git a/subsys/net/lib/lwm2m/lwm2m_message_handling.c b/subsys/net/lib/lwm2m/lwm2m_message_handling.c
index ac765aa0fc6716f..abc8a39ae8f3e75 100644
--- a/subsys/net/lib/lwm2m/lwm2m_message_handling.c
+++ b/subsys/net/lib/lwm2m/lwm2m_message_handling.c
@@ -82,6 +82,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 /* Resources */
 
 /* Shared set of in-flight LwM2M messages */
+static K_MUTEX_DEFINE(msg_lock);
 static struct lwm2m_message messages[CONFIG_LWM2M_ENGINE_MAX_MESSAGES];
 static struct lwm2m_block_context block1_contexts[NUM_BLOCK1_CONTEXT];
 static struct lwm2m_message *ongoing_block2_tx;
@@ -517,18 +518,25 @@ struct lwm2m_message *find_msg(struct coap_pending *pending, struct coap_reply *
 	return NULL;
 }
 
+
 struct lwm2m_message *lwm2m_get_message(struct lwm2m_ctx *client_ctx)
 {
+	struct lwm2m_message *msg = NULL;
 	size_t i;
 
+	k_mutex_lock(&msg_lock, K_FOREVER);
+
 	for (i = 0; i < CONFIG_LWM2M_ENGINE_MAX_MESSAGES; i++) {
 		if (!messages[i].ctx) {
 			messages[i].ctx = client_ctx;
-			return &messages[i];
+			msg = &messages[i];
+			break;
 		}
 	}
 
-	return NULL;
+	k_mutex_unlock(&msg_lock);
+
+	return msg;
 }
 
 void lm2m_message_clear_allocations(struct lwm2m_message *msg)
@@ -561,11 +569,13 @@ void lwm2m_reset_message(struct lwm2m_message *msg, bool release)
 	}
 
 	if (release) {
+		k_mutex_lock(&msg_lock, K_FOREVER);
 #if defined(CONFIG_LWM2M_COAP_BLOCK_TRANSFER)
 		release_output_block_ctx(&msg->out.block_ctx);
 		release_body_encode_buffer(&msg->body_encode_buffer.data);
 #endif
 		(void)memset(msg, 0, sizeof(*msg));
+		k_mutex_unlock(&msg_lock);
 	} else {
 		msg->message_timeout_cb = NULL;
 		(void)memset(&msg->cpkt, 0, sizeof(msg->cpkt));