diff --git a/cpukit/posix/include/rtems/posix/mqueue.h b/cpukit/posix/include/rtems/posix/mqueue.h
index f1222c08e9..7b831ac141 100644
--- a/cpukit/posix/include/rtems/posix/mqueue.h
+++ b/cpukit/posix/include/rtems/posix/mqueue.h
@@ -126,7 +126,7 @@ ssize_t _POSIX_Message_queue_Receive_support(
 int _POSIX_Message_queue_Send_support(
   mqd_t               mqdes,
   const char         *msg_ptr,
-  uint32_t            msg_len,
+  size_t              msg_len,
   uint32_t            msg_prio,
   Watchdog_Interval   timeout
 );
diff --git a/cpukit/posix/src/mqueuesendsupp.c b/cpukit/posix/src/mqueuesendsupp.c
index 33109465e6..60f48fcdba 100644
--- a/cpukit/posix/src/mqueuesendsupp.c
+++ b/cpukit/posix/src/mqueuesendsupp.c
@@ -41,7 +41,7 @@
 int _POSIX_Message_queue_Send_support(
   mqd_t               mqdes,
   const char         *msg_ptr,
-  uint32_t            msg_len,
+  size_t              msg_len,
   uint32_t            msg_prio,
   Watchdog_Interval   timeout
 )