diff --git a/modules/libcom/src/error/errlog.c b/modules/libcom/src/error/errlog.c
index 7ed6a8bd7..8c1c9c0ce 100644
--- a/modules/libcom/src/error/errlog.c
+++ b/modules/libcom/src/error/errlog.c
@@ -65,6 +65,7 @@ typedef struct listenerNode{
 typedef struct {
     char *base;
     size_t pos;
+    size_t nchar;
 } buffer_t;
 
 static struct {
@@ -91,8 +92,8 @@ static struct {
 
     /* A loop counter maintained by errlogThread. */
     epicsUInt32 flushSeq;
-    size_t nFlushers;
-    size_t nLost;
+    unsigned long nFlushers;
+    unsigned long nLost;
 
     /* 'log' and 'print' combine to form a double buffer. */
     buffer_t *log;
@@ -118,9 +119,14 @@ char* msgbufAlloc(void)
 
     errlogInit(0);
     epicsMutexMustLock(pvt.msgQueueLock); /* matched in msgbufCommit() */
-    if(pvt.bufSize - pvt.log->pos >= 1+pvt.maxMsgSize) {
+    if(pvt.bufSize - pvt.log->pos - pvt.log->nchar >= 1+pvt.maxMsgSize) {
         /* there is enough space for the worst cast */
         ret = pvt.log->base + pvt.log->pos;
+        if (pvt.log->nchar) {
+            /* append to last message */
+            return ret + 1 + pvt.log->nchar;
+        }
+        /* new message */
         ret[0] = ERL_STATE_WRITE;
         ret++;
     }
@@ -138,7 +144,7 @@ size_t msgbufCommit(size_t nchar, int localEcho)
     int isOkToBlock = epicsThreadIsOkToBlock();
     int wasEmpty = pvt.log->pos==0;
     int atExit = pvt.atExit;
-    char *start = pvt.log->base + pvt.log->pos;
+    char *start = pvt.log->base + pvt.log->pos + pvt.log->nchar;
 
     /* nchar returned by snprintf() is >= maxMsgSize when truncated */
     if(nchar >= pvt.maxMsgSize) {
@@ -157,15 +163,20 @@ size_t msgbufCommit(size_t nchar, int localEcho)
          */
         fprintf(pvt.console, "%s", start);
 
-    } else {
-        start[0u] = ERL_STATE_READY | (localEcho ? ERL_LOCALECHO : 0);
+    } else if (start[nchar] != '\n') {
+        /* incomplete message, prepare to append */
+        pvt.log->nchar += nchar;
 
-        pvt.log->pos += 1u + nchar + 1u;
+    } else {
+        pvt.log->base[pvt.log->pos] = ERL_STATE_READY | (localEcho ? ERL_LOCALECHO : 0);
+
+        pvt.log->pos += 1 + pvt.log->nchar + nchar + 1;
+        pvt.log->nchar = 0;
     }
 
     epicsMutexUnlock(pvt.msgQueueLock); /* matched in msgbufAlloc() */
 
-    if(wasEmpty && !atExit)
+    if(wasEmpty && !atExit && !pvt.log->nchar)
         epicsEventMustTrigger(pvt.waitForWork);
 
     if(localEcho && isOkToBlock && !atExit)
@@ -519,7 +530,7 @@ static void errlogThread(void)
 
         } else {
             /* snapshot and swap buffers for use while unlocked */
-            size_t nLost = pvt.nLost;
+            unsigned long nLost = pvt.nLost;
             FILE *console = pvt.toConsole ? pvt.console : NULL;
             size_t pos = 0u;
             buffer_t *print;
@@ -564,7 +575,7 @@ static void errlogThread(void)
             print->pos = 0u;
 
             if(nLost && console)
-                fprintf(console, "errlog: lost %zu messages\n", nLost);
+                fprintf(console, "errlog: lost %lu messages\n", nLost);
 
             if(console)
                 fflush(console);