diff --git a/fs/mqueue/mq_open.c b/fs/mqueue/mq_open.c
index 627e57f4dd..d561439ef0 100644
--- a/fs/mqueue/mq_open.c
+++ b/fs/mqueue/mq_open.c
@@ -191,6 +191,11 @@ static int file_mq_vopen(FAR struct file *mq, FAR const char *mq_name,
 
       mode = va_arg(ap, mode_t);
       attr = va_arg(ap, FAR struct mq_attr *);
+      if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
+        {
+          ret = -EINVAL;
+          goto errout;
+        }
     }
 
   mode &= ~umask;
diff --git a/include/mqueue.h b/include/mqueue.h
index ed3d271c66..361e8e66fd 100644
--- a/include/mqueue.h
+++ b/include/mqueue.h
@@ -42,10 +42,10 @@
 
 struct mq_attr
 {
-  size_t         mq_maxmsg;    /* Max number of messages in queue */
-  size_t         mq_msgsize;   /* Max message size */
-  unsigned       mq_flags;     /* Queue flags */
-  size_t         mq_curmsgs;   /* Number of messages currently in queue */
+  long    mq_maxmsg;    /* Max number of messages in queue */
+  long    mq_msgsize;   /* Max message size */
+  long    mq_flags;     /* Queue flags */
+  long    mq_curmsgs;   /* Number of messages currently in queue */
 };
 
 /* Message queue descriptor */