diff --git a/modules/ca/src/client/cac.cpp b/modules/ca/src/client/cac.cpp
index cb09d8d78..fd641ad21 100644
--- a/modules/ca/src/client/cac.cpp
+++ b/modules/ca/src/client/cac.cpp
@@ -25,6 +25,7 @@
 #include <stdexcept>
 #include <string> // vxWorks 6.0 requires this include
 
+#include "epicsStdio.h"
 #include "dbDefs.h"
 #include "epicsGuard.h"
 #include "epicsVersion.h"
@@ -1008,7 +1009,7 @@ bool cac::defaultExcep (
     char buf[512];
     char hostName[64];
     iiu.getHostName ( guard, hostName, sizeof ( hostName ) );
-    snprintf( buf, sizeof(buf), "host=%s ctx=%.400s", hostName, pCtx );
+    epicsSnprintf( buf, sizeof(buf), "host=%s ctx=%.400s", hostName, pCtx );
     this->notify.exception ( guard, status, buf, 0, 0u );
     return true;
 }
@@ -1312,7 +1313,7 @@ void cac::pvMultiplyDefinedNotify ( msgForMultiplyDefinedPV & mfmdpv,
     const char * pChannelName, const char * pAcc, const char * pRej )
 {
     char buf[256];
-    snprintf( buf, sizeof(buf), "Channel: \"%.64s\", Connecting to: %.64s, Ignored: %.64s",
+    epicsSnprintf( buf, sizeof(buf), "Channel: \"%.64s\", Connecting to: %.64s, Ignored: %.64s",
             pChannelName, pAcc, pRej );
     {
         callbackManager mgr ( this->notify, this->cbMutex );
diff --git a/modules/libcom/src/osi/epicsTime.cpp b/modules/libcom/src/osi/epicsTime.cpp
index ae7eb25eb..b78191f69 100644
--- a/modules/libcom/src/osi/epicsTime.cpp
+++ b/modules/libcom/src/osi/epicsTime.cpp
@@ -238,7 +238,7 @@ size_t epicsStdCall epicsTimeToStrftime (char *pBuff, size_t bufLength, const ch
                     // convert nanosecs to integer of correct range
                     frac /= div[fracWid];
                     char fracFormat[32];
-                    snprintf ( fracFormat, sizeof ( fracFormat ), "%%0%lulu", fracWid );
+                    epicsSnprintf ( fracFormat, sizeof ( fracFormat ), "%%0%lulu", fracWid );
                     int status = epicsSnprintf ( pBufCur, bufLenLeft, fracFormat, frac );
                     if ( status > 0 ) {
                         unsigned long nChar = static_cast < unsigned long > ( status );
diff --git a/modules/libcom/test/epicsEventTest.cpp b/modules/libcom/test/epicsEventTest.cpp
index 7f93c36a9..f9fa87198 100644
--- a/modules/libcom/test/epicsEventTest.cpp
+++ b/modules/libcom/test/epicsEventTest.cpp
@@ -16,12 +16,12 @@
 #include <stdlib.h>
 #include <stddef.h>
 #include <string.h>
-#include <stdio.h>
 #include <errno.h>
 #include <time.h>
 #include <math.h>
 #include <float.h>
 
+#include "epicsStdio.h"
 #include "epicsThread.h"
 #include "epicsEvent.h"
 #include "epicsMutex.h"
@@ -244,7 +244,7 @@ MAIN(epicsEventTest)
     name = (char **)calloc(nthreads, sizeof(char *));
     for(int i = 0; i < nthreads; i++) {
         name[i] = (char *)calloc(16, sizeof(char));
-        snprintf(name[i], 16, "producer %d",i);
+        epicsSnprintf(name[i], 16, "producer %d",i);
         id[i] = epicsThreadCreate(name[i], 40, stackSize, producer, pinfo);
         epicsThreadSleep(0.1);
     }
diff --git a/modules/libcom/test/epicsMessageQueueTest.cpp b/modules/libcom/test/epicsMessageQueueTest.cpp
index d78cfdbd9..fc5a903b9 100644
--- a/modules/libcom/test/epicsMessageQueueTest.cpp
+++ b/modules/libcom/test/epicsMessageQueueTest.cpp
@@ -10,11 +10,11 @@
 /*
  *      Author  W. Eric Norum
  */
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 
+#include "epicsStdio.h"
 #include "epicsMessageQueue.h"
 #include "epicsThread.h"
 #include "epicsExit.h"
@@ -232,7 +232,7 @@ sender(void *arg)
     int i = 0;
 
     while (!sendExit) {
-        len = snprintf(cbuf, sizeof(cbuf), "%s -- %d.", epicsThreadGetNameSelf(), ++i);
+        len = epicsSnprintf(cbuf, sizeof(cbuf), "%s -- %d.", epicsThreadGetNameSelf(), ++i);
         while (q->trySend((void *)cbuf, len) < 0)
             epicsThreadSleep(0.005 * (randBelow(5)));
         epicsThreadSleep(0.005 * (randBelow(20)));
@@ -421,7 +421,7 @@ extern "C" void messageQueueTest(void *parm)
             epicsThreadPriorityHigh,
             epicsThreadPriorityHigh
         };
-        snprintf(name, sizeof(name), "Sender %d", i+1);
+        epicsSnprintf(name, sizeof(name), "Sender %d", i+1);
         opts.priority = pri[i];
         senderId[i] = epicsThreadCreateOpt(name, sender, &q1, &opts);
         if (!senderId[i])
diff --git a/modules/libcom/test/epicsMutexTest.cpp b/modules/libcom/test/epicsMutexTest.cpp
index 5228e9bed..1342b903e 100644
--- a/modules/libcom/test/epicsMutexTest.cpp
+++ b/modules/libcom/test/epicsMutexTest.cpp
@@ -18,10 +18,10 @@
 #include <stdlib.h>
 #include <stddef.h>
 #include <string.h>
-#include <stdio.h>
 #include <errno.h>
 #include <time.h>
 
+#include "epicsStdio.h"
 #include "epicsTime.h"
 #include "epicsThread.h"
 #include "epicsMutex.h"
@@ -266,7 +266,7 @@ MAIN(epicsMutexTest)
     stackSize = epicsThreadGetStackSize(epicsThreadStackSmall);
     for(i=0; i<nthreads; i++) {
         name[i] = (char *)calloc(10,sizeof(char));
-        snprintf(name[i], 10, "task%d",i);
+        epicsSnprintf(name[i], 10, "task%d",i);
         pinfo[i] = (info *)calloc(1,sizeof(info));
         pinfo[i]->threadnum = i;
         pinfo[i]->mutex = mutex;
diff --git a/modules/libcom/test/epicsThreadTest.cpp b/modules/libcom/test/epicsThreadTest.cpp
index 573739f39..6d43e71dc 100644
--- a/modules/libcom/test/epicsThreadTest.cpp
+++ b/modules/libcom/test/epicsThreadTest.cpp
@@ -13,11 +13,11 @@
 #include <stdlib.h>
 #include <stddef.h>
 #include <string.h>
-#include <stdio.h>
 #include <errno.h>
 #include <time.h>
 #include <math.h>
 
+#include "epicsStdio.h"
 #include "epicsThread.h"
 #include "epicsEvent.h"
 #include "epicsTime.h"
@@ -73,7 +73,7 @@ void testMyThread()
     int startPriority = 0;
     for (int i = 0; i < ntasks; i++) {
         char name[10];
-        snprintf(name, sizeof(name), "t%d", i);
+        epicsSnprintf(name, sizeof(name), "t%d", i);
         myThreads[i] = new myThread(i, name);
         if (i == 0)
             startPriority = myThreads[i]->thread.getPriority();