diff --git a/minix/kernel/mqueue.c b/minix/kernel/mqueue.c
index efe38f334..0093db282 100644
--- a/minix/kernel/mqueue.c
+++ b/minix/kernel/mqueue.c
@@ -21,6 +21,7 @@ int initialize_message_queues(void)
 
 	for (int i = 0; i < MAX_QUEUES; i++) {
 		mq.queue_slot_empty[i] = EMPTY;
+		mq.msg[i].num_users = 0;
 		mq.msg[i].num_msgs = 0;
 	}
 
@@ -32,7 +33,8 @@ int deinitialize_message_queues(void)
 	mq.num_queues = -1;
 	for (int i = 0; i < MAX_QUEUES; i++) {
 		mq.msg[i].num_msgs = -1;
-		mq.queue_slot_empty[i] = -1;
+		mq.msg[i].num_users = -1;
+		mq.queue_slot_empty[i] = EMPTY;
 	}
 
 	return 0;
@@ -42,7 +44,7 @@ int mq_open(const char *name, int oflag)
 {
 	mqd_t mqd;
 
-	if (mq.num_queues == MAX_QUEUES)
+	if (mq.num_queues >= MAX_QUEUES)
 		return EMQUEUEFULL;
 
 	if (strlen(name) > NAME_SIZE)
@@ -50,18 +52,21 @@ int mq_open(const char *name, int oflag)
 
 	for (int i = 0; i < MAX_QUEUES; i++)
 		if (mq.queue_slot_empty[i] == NOT_EMPTY)
-			if (strcmp(mq.msg[i].name, name) == 0)
+			if (strcmp(mq.msg[i].name, name) == 0) {
+				mq.msg[i].num_users++;
 				return (mqd_t) i;
+			}
 
 	for (int i = 0; i < MAX_QUEUES; i++) {
 		if (mq.queue_slot_empty[i] == EMPTY) {
 			mqd = i;
 			mq.queue_slot_empty[i] = NOT_EMPTY;
 			mq.num_queues++;
+			mq.msg[i].num_users++;
 			strncpy(mq.msg[i].name, name, strlen(name));
 
 			for (int j = 0; j < MAX_MESSAGES; j++) {
-				mq.msg[i].msg_slot_empty[j] = NOT_EMPTY;
+				mq.msg[i].msg_slot_empty[j] = EMPTY;
 				mq.msg[i].msge[j].priority = DEFAULT_PRIO;
 				for (int k = 0; k < MAX_RECEIVERS; k++)
 					mq.msg[i].msge[j].dst[k] = EMPTY;
@@ -81,9 +86,12 @@ int mq_close(mqd_t mqdes)
 	if (mq.queue_slot_empty[mqdes] == EMPTY)
 		return EMSGNOTFOUND;
 
-	mq.msg[mqdes].num_msgs = 0;
-	mq.queue_slot_empty[mqdes] = EMPTY;
-	mq.num_queues--;
+	mq.msg[mqdes].num_users--;
+	if (mq.msg[mqdes].num_users == 0) {
+		mq.msg[mqdes].num_msgs = 0;
+		mq.queue_slot_empty[mqdes] = EMPTY;
+		mq.num_queues--;
+	}
 
 	return 0;
 }
@@ -96,7 +104,7 @@ int mq_send(mqd_t mqdes, const char *msg_ptr, unsigned int msg_prio, endpoint_t
 	if (mq.queue_slot_empty[mqdes] == EMPTY)
 		return EMSGNOTFOUND;
 
-	if (mq.msg[mqdes].num_msgs >= MAX_MESSAGES)
+	if (mq.msg[mqdes].num_msgs > MAX_MESSAGES)
 		return EMSGFULL;
 
 	int empty_slot_pos;
@@ -106,9 +114,11 @@ int mq_send(mqd_t mqdes, const char *msg_ptr, unsigned int msg_prio, endpoint_t
 			break;
 		}
 
+	memset(mq.msg[mqdes].msge[empty_slot_pos].msg, 0, MAX_PAYLOAD);
 	memcpy(mq.msg[mqdes].msge[empty_slot_pos].msg,
 	       msg_ptr, MAX_PAYLOAD);
 	mq.msg[mqdes].msge[empty_slot_pos].src = src;
+	mq.msg[mqdes].msge[empty_slot_pos].priority = msg_prio;
 	mq.msg[mqdes].msg_slot_empty[empty_slot_pos] = NOT_EMPTY;
 
 	for (int i = 0; i < MAX_RECEIVERS; i++)
@@ -128,9 +138,6 @@ size_t mq_receive(mqd_t mqdes, char *msg_ptr, unsigned int msg_prio, endpoint_t
 	if (mq.queue_slot_empty[mqdes] == EMPTY)
 		return EMSGNOTFOUND;
 
-	if (mq.msg[mqdes].num_msgs >= MAX_MESSAGES)
-		return EMSGFULL;
-
 	if (mq.msg[mqdes].num_msgs == 0)
 		return EMSGEMPTY;
 
@@ -158,15 +165,15 @@ int find_max(int n1, int n2)
 	return n2;
 }
 
-int message_index_with_highprio(mqdes, dst)
+int message_index_with_highprio(int mqdes, endpoint_t dst)
 {
 	int prio;
 	int max_prio = -1;
 	int index = -1;
 
 	for (int i = 0; i < MAX_MESSAGES; i++) {
-		prio = mq.msg[mqdes].msge[i].priority;
 		if (mq.msg[mqdes].msg_slot_empty[i] == NOT_EMPTY) {
+			prio = mq.msg[mqdes].msge[i].priority;
 			for (int j = 0; j < MAX_RECEIVERS; j++) {
 				if (mq.msg[mqdes].msge[i].dst[j] == dst) {
 					if (max_prio < find_max(max_prio, prio)) {
diff --git a/minix/kernel/mqueue.h b/minix/kernel/mqueue.h
index e85607191..180e7dc79 100644
--- a/minix/kernel/mqueue.h
+++ b/minix/kernel/mqueue.h
@@ -32,6 +32,7 @@ typedef struct message_entity {
 typedef struct messageq {
 	char name[NAME_SIZE];
 	int num_msgs;
+	int num_users;
 	message_entity msge[MAX_MESSAGES];
 	int msg_slot_empty[MAX_MESSAGES];
 } messageq;
diff --git a/minix/lib/libsys/sys_mq_send.c b/minix/lib/libsys/sys_mq_send.c
index d4e0de237..2e0f8f087 100644
--- a/minix/lib/libsys/sys_mq_send.c
+++ b/minix/lib/libsys/sys_mq_send.c
@@ -13,6 +13,7 @@ int sys_mq_send(int mqdes, const char *msg_ptr, pid_t dst[], unsigned int msg_pr
 	message m;
 
 	m.m_lsys_krn_sys_mqueue_send.mqdes = mqdes;
+	m.m_lsys_krn_sys_mqueue_send.msg_prio = msg_prio;
 	for (int i = 0; i < MAX_RECEIVERS; i++) {
 		if (dst[i] == -1) {
 			m.m_lsys_krn_sys_mqueue_send.dst[i] = dst[i];