diff --git a/src/libCom/osi/os/RTEMS/osdMutex.c b/src/libCom/osi/os/RTEMS/osdMutex.c
index 0bdd29875..5a02607f1 100644
--- a/src/libCom/osi/os/RTEMS/osdMutex.c
+++ b/src/libCom/osi/os/RTEMS/osdMutex.c
@@ -39,7 +39,7 @@ unsigned long semMstat[4];
 #define SEMSTAT(i) 
 #endif
 
-epicsMutexOSD *
+struct epicsMutexOSD *
 epicsMutexOsdCreate(void)
 {
     rtems_status_code sc;