diff --git a/src/libCom/osi/os/default/osdMessageQueue.cpp b/src/libCom/osi/os/default/osdMessageQueue.cpp
index 2e5343bbc..9f589aaf4 100644
--- a/src/libCom/osi/os/default/osdMessageQueue.cpp
+++ b/src/libCom/osi/os/default/osdMessageQueue.cpp
@@ -135,21 +135,21 @@ getEventNode(epicsMessageQueueId pmsg)
 
     evp = reinterpret_cast < struct eventNode * > ( ellGet(&pmsg->eventFreeList) );
     if (evp == NULL) {
-        epicsEventId eid = epicsEventCreate(epicsEventEmpty);
         evp = (struct eventNode *) calloc(1, sizeof(*evp));
-        if(!evp || !eid) {
-            free(evp);
-            if(eid)
-                epicsEventDestroy(eid);
-            return NULL;
+        if (evp) {
+            evp->event = epicsEventCreate(epicsEventEmpty);
+            if (evp->event == NULL) {
+                free(evp);
+                return NULL;
+            }
         }
-        evp->event = eid;
     }
     return evp;
 }
 
 static int
-mySend(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait, bool haveTimeout, double timeout)
+mySend(epicsMessageQueueId pmsg, void *message, unsigned int size,
+    double timeout)
 {
     char *myInPtr, *nextPtr;
     struct threadNode *pthr;
@@ -160,15 +160,14 @@ mySend(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait, bo
     /*
      * See if message can be sent
      */
-    if(epicsMutexLock(pmsg->mutex)!=epicsMutexLockOK)
-        return -1;
+    epicsMutexMustLock(pmsg->mutex);
 
     if ((pmsg->numberOfSendersWaiting > 0)
      || (pmsg->full && (ellFirst(&pmsg->receiveQueue) == NULL))) {
         /*
          * Return if not allowed to wait
          */
-        if (!wait) {
+        if (timeout == 0) {
             epicsMutexUnlock(pmsg->mutex);
             return -1;
         }
@@ -189,15 +188,13 @@ mySend(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait, bo
 
         epicsMutexUnlock(pmsg->mutex);
 
-        if(haveTimeout)
-            epicsEventWaitWithTimeout(threadNode.evp->event, timeout);
+        epicsEventStatus status;
+        if (timeout > 0)
+            status = epicsEventWaitWithTimeout(threadNode.evp->event, timeout);
         else
-            epicsEventWait(threadNode.evp->event);
+            status = epicsEventWait(threadNode.evp->event);
 
-        if(epicsMutexLock(pmsg->mutex)!=epicsMutexLockOK){
-            freeEventNode(threadNode.evp);
-            return -1;
-        }
+        epicsMutexMustLock(pmsg->mutex);
 
         if(!threadNode.eventSent)
             ellDelete(&pmsg->sendQueue, &threadNode.link);
@@ -205,7 +202,8 @@ mySend(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait, bo
 
         ellAdd(&pmsg->eventFreeList, &threadNode.evp->link);
 
-        if (pmsg->full && (ellFirst(&pmsg->receiveQueue) == NULL)) {
+        if ((pmsg->full && (ellFirst(&pmsg->receiveQueue) == NULL)) ||
+            status != epicsEventOK) {
             epicsMutexUnlock(pmsg->mutex);
             return -1;
         }
@@ -243,25 +241,29 @@ mySend(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait, bo
 }
 
 epicsShareFunc int epicsShareAPI
-epicsMessageQueueTrySend(epicsMessageQueueId pmsg, void *message, unsigned int size)
+epicsMessageQueueTrySend(epicsMessageQueueId pmsg, void *message,
+    unsigned int size)
 {
-    return mySend(pmsg, message, size, false, false, 0.0);
+    return mySend(pmsg, message, size, 0);
 }
 
 epicsShareFunc int epicsShareAPI
-epicsMessageQueueSend(epicsMessageQueueId pmsg, void *message, unsigned int size)
+epicsMessageQueueSend(epicsMessageQueueId pmsg, void *message,
+    unsigned int size)
 {
-    return mySend(pmsg, message, size, true, false, 0.0);
+    return mySend(pmsg, message, size, -1);
 }
 
 epicsShareFunc int epicsShareAPI
-epicsMessageQueueSendWithTimeout(epicsMessageQueueId pmsg, void *message, unsigned int size, double timeout)
+epicsMessageQueueSendWithTimeout(epicsMessageQueueId pmsg, void *message,
+    unsigned int size, double timeout)
 {
-    return mySend(pmsg, message, size, true, true, timeout);
+    return mySend(pmsg, message, size, timeout);
 }
 
 static int
-myReceive(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait, bool haveTimeout, double timeout)
+myReceive(epicsMessageQueueId pmsg, void *message, unsigned int size,
+    double timeout)
 {
     char *myOutPtr;
     unsigned long l;
@@ -270,8 +272,7 @@ myReceive(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait,
     /*
      * If there's a message on the queue, copy it
      */
-    if(epicsMutexLock(pmsg->mutex)!=epicsMutexLockOK)
-        return -1;
+    epicsMutexMustLock(pmsg->mutex);
 
     myOutPtr = (char *)pmsg->outPtr;
     if ((myOutPtr != pmsg->inPtr) || pmsg->full) {
@@ -305,7 +306,7 @@ myReceive(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait,
     /*
      * Return if not allowed to wait
      */
-    if (!wait) {
+    if (timeout == 0) {
         epicsMutexUnlock(pmsg->mutex);
         return -1;
     }
@@ -328,7 +329,7 @@ myReceive(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait,
     threadNode.size = size;
     threadNode.eventSent = false;
 
-    if(!threadNode.evp) {
+    if (!threadNode.evp) {
         epicsMutexUnlock(pmsg->mutex);
         return -1;
     }
@@ -336,43 +337,45 @@ myReceive(epicsMessageQueueId pmsg, void *message, unsigned int size, bool wait,
     ellAdd(&pmsg->receiveQueue, &threadNode.link);
     epicsMutexUnlock(pmsg->mutex);
 
-    if(haveTimeout)
-        epicsEventWaitWithTimeout(threadNode.evp->event, timeout);
+    epicsEventStatus status;
+    if (timeout > 0)
+        status = epicsEventWaitWithTimeout(threadNode.evp->event, timeout);
     else
-        epicsEventWait(threadNode.evp->event);
+        status = epicsEventWait(threadNode.evp->event);
 
-    if(epicsMutexLock(pmsg->mutex)!=epicsMutexLockOK){
-        freeEventNode(threadNode.evp);
-        return -1;
-    }
+    epicsMutexMustLock(pmsg->mutex);
 
-    if(!threadNode.eventSent)
+    if (!threadNode.eventSent)
         ellDelete(&pmsg->receiveQueue, &threadNode.link);
     ellAdd(&pmsg->eventFreeList, &threadNode.evp->link);
 
     epicsMutexUnlock(pmsg->mutex);
 
-    if(threadNode.eventSent && (threadNode.size <= size))
+    if (threadNode.eventSent && (threadNode.size <= size) &&
+        status == epicsEventOK)
         return threadNode.size;
     return -1;
 }
 
 epicsShareFunc int epicsShareAPI
-epicsMessageQueueTryReceive(epicsMessageQueueId pmsg, void *message, unsigned int size)
+epicsMessageQueueTryReceive(epicsMessageQueueId pmsg, void *message,
+    unsigned int size)
 {
-    return myReceive(pmsg, message, size, false, false, 0.0);
+    return myReceive(pmsg, message, size, 0);
 }
 
 epicsShareFunc int epicsShareAPI
-epicsMessageQueueReceive(epicsMessageQueueId pmsg, void *message, unsigned int size)
+epicsMessageQueueReceive(epicsMessageQueueId pmsg, void *message,
+    unsigned int size)
 {
-    return myReceive(pmsg, message, size, true, false, 0.0);
+    return myReceive(pmsg, message, size, -1);
 }
 
 epicsShareFunc int epicsShareAPI
-epicsMessageQueueReceiveWithTimeout(epicsMessageQueueId pmsg, void *message, unsigned int size, double timeout)
+epicsMessageQueueReceiveWithTimeout(epicsMessageQueueId pmsg, void *message,
+    unsigned int size, double timeout)
 {
-    return myReceive(pmsg, message, size, true, true, timeout);
+    return myReceive(pmsg, message, size, timeout);
 }
 
 epicsShareFunc int epicsShareAPI
diff --git a/src/libCom/osi/os/posix/osdMutex.c b/src/libCom/osi/os/posix/osdMutex.c
index ec1e7097c..44a3c4d6e 100644
--- a/src/libCom/osi/os/posix/osdMutex.c
+++ b/src/libCom/osi/os/posix/osdMutex.c
@@ -245,7 +245,7 @@ void epicsMutexOsdUnlock(struct epicsMutexOSD * pmutex)
         pmutex->owned = 0;
         pmutex->ownerTid = 0;
         status = pthread_cond_signal(&pmutex->waitToBeOwner);
-        checkStatus(status, "pthread_cond_signal epicsMutexOsdUnlock");
+        checkStatusQuit(status, "pthread_cond_signal epicsMutexOsdUnlock", "epicsMutexOsdUnlock");
     }
 
     status = pthread_mutex_unlock(&pmutex->lock);
diff --git a/src/libCom/osi/os/posix/osdThread.c b/src/libCom/osi/os/posix/osdThread.c
index fdf475802..3c8844f70 100644
--- a/src/libCom/osi/os/posix/osdThread.c
+++ b/src/libCom/osi/os/posix/osdThread.c
@@ -3,11 +3,9 @@
 *     National Laboratory.
 * Copyright (c) 2002 The Regents of the University of California, as
 *     Operator of Los Alamos National Laboratory.
-* EPICS BASE Versions 3.13.7
-* and higher are distributed subject to a Software License Agreement found
+* EPICS BASE is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution. 
 \*************************************************************************/
-/* epicsThread.c */
 
 /* Author:  Marty Kraimer Date:    18JAN2000 */
 
@@ -72,7 +70,7 @@ typedef struct epicsThreadOSD {
     int                isFifoScheduled;
     int                isOnThreadList;
     unsigned int       osiPriority;
-    char              *name;
+    char               name[1];     /* actually larger */
 } epicsThreadOSD;
 
 #ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
@@ -158,7 +156,8 @@ static epicsThreadOSD * create_threadInfo(const char *name)
 {
     epicsThreadOSD *pthreadInfo;
 
-    pthreadInfo = calloc(1,sizeof(*pthreadInfo) + strlen(name)+1);
+    /* sizeof(epicsThreadOSD) includes one byte for the '\0' */
+    pthreadInfo = calloc(1,sizeof(*pthreadInfo) + strlen(name));
     if(!pthreadInfo)
         return NULL;
     pthreadInfo->suspendEvent = epicsEventCreate(epicsEventEmpty);
@@ -166,7 +165,6 @@ static epicsThreadOSD * create_threadInfo(const char *name)
         free(pthreadInfo);
         return NULL;
     }
-    pthreadInfo->name = (char*)&pthreadInfo[1];
     strcpy(pthreadInfo->name, name);
     return pthreadInfo;
 }
@@ -206,17 +204,13 @@ static void free_threadInfo(epicsThreadOSD *pthreadInfo)
     int status;
 
     status = mutexLock(&listLock);
-    checkStatus(status,"pthread_mutex_lock free_threadInfo");
-    if(status)
-        return;
+    checkStatusQuit(status,"pthread_mutex_lock","free_threadInfo");
     if(pthreadInfo->isOnThreadList) ellDelete(&pthreadList,&pthreadInfo->node);
     status = pthread_mutex_unlock(&listLock);
-    checkStatus(status,"pthread_mutex_unlock free_threadInfo");
+    checkStatusQuit(status,"pthread_mutex_unlock","free_threadInfo");
     epicsEventDestroy(pthreadInfo->suspendEvent);
     status = pthread_attr_destroy(&pthreadInfo->attr);
-    checkStatus(status,"pthread_attr_destroy free_threadInfo");
-    if(status)
-        return;
+    checkStatusQuit(status,"pthread_attr_destroy","free_threadInfo");
     free(pthreadInfo);
 }
 
@@ -539,8 +533,7 @@ static epicsThreadOSD *createImplicit(void)
     tid = pthread_self();
     sprintf(name, "non-EPICS_%ld", (long)tid);
     pthreadInfo = create_threadInfo(name);
-    if(!pthreadInfo)
-        return NULL;
+    assert(pthreadInfo);
     pthreadInfo->tid = tid;
     pthreadInfo->osiPriority = 0;
 #if defined (_POSIX_THREAD_PRIORITY_SCHEDULING) 
@@ -823,6 +816,7 @@ epicsShareFunc void epicsShareAPI epicsThreadShow(epicsThreadId showThread, unsi
     }
     status = pthread_mutex_unlock(&listLock);
     checkStatus(status,"pthread_mutex_unlock epicsThreadShowAll");
+    if(status) return;
     if (!found)
         printf("Thread %#lx (%lu) not found.\n", (unsigned long)showThread, (unsigned long)showThread);
 }
diff --git a/src/libCom/ring/epicsRingBytes.c b/src/libCom/ring/epicsRingBytes.c
index f116a838a..2c15ee8f1 100644
--- a/src/libCom/ring/epicsRingBytes.c
+++ b/src/libCom/ring/epicsRingBytes.c
@@ -33,7 +33,7 @@ typedef struct ringPvt {
     volatile int   nextPut;
     volatile int   nextGet;
     int            size;
-    volatile char *buffer;
+    volatile char buffer[1]; /* actually larger */
 }ringPvt;
 
 epicsShareFunc epicsRingBytesId  epicsShareAPI epicsRingBytesCreate(int size)
@@ -42,7 +42,6 @@ epicsShareFunc epicsRingBytesId  epicsShareAPI epicsRingBytesCreate(int size)
     if(!pring)
         return NULL;
     pring->size = size + SLOP;
-    pring->buffer = (char*)&pring[1];
     pring->nextGet = 0;
     pring->nextPut = 0;
     return((void *)pring);