diff --git a/modules/libcom/src/osi/os/WIN32/osdSock.c b/modules/libcom/src/osi/os/WIN32/osdSock.c
index 53d240a7f..6b7d6c8b8 100644
--- a/modules/libcom/src/osi/os/WIN32/osdSock.c
+++ b/modules/libcom/src/osi/os/WIN32/osdSock.c
@@ -63,10 +63,10 @@ LIBCOM_API int epicsStdCall osiSockAttach()
         DWORD titleLength = GetConsoleTitle(title, sizeof(title));
         if (titleLength) {
             titleLength = strlen (title);
-            strncat (title, " " EPICS_VERSION_STRING, sizeof(title));
+            strncat (title, " " EPICS_VERSION_STRING, sizeof(title)-1);
         }
         else {
-            strncpy(title, EPICS_VERSION_STRING, sizeof(title));
+            strncpy(title, EPICS_VERSION_STRING, sizeof(title)-1);
         }
         title[sizeof(title)-1]= '\0';
         SetConsoleTitle(title);