--- ckcfns.c
+++ ckcfns.c
@@ -5557,7 +5557,7 @@
 		fromgetpath = 0;
 		if (server && !isabsolute(filnam) && (ngetpath > i)) {
 		    ckstrncpy(fullname,getpath[i],CKMAXPATH+1);
-		    strncat(fullname,filnam,CKMAXPATH);
+		    strncat(fullname,filnam,CKMAXPATH-strlen(fullname)-1);
 		    debug(F111,"gnfile getpath",fullname,i);
 		    fromgetpath = 1;
 		    i++;
--- ckcftp.c
+++ ckcftp.c
@@ -1899,8 +1899,8 @@
     if (t2 > -1L) {
         ftplogprev = t2;
         p = hhmmss(t2);
-        strncat(ftplogbuf,"E=",CXLOGBUFL); /* Append to log record */
-        strncat(ftplogbuf,p,CXLOGBUFL);
+        strncat(ftplogbuf,"E=",CXLOGBUFL-strlen(ftplogbuf)-1); /* Append to log record */
+        strncat(ftplogbuf,p,CXLOGBUFL-strlen(ftplogbuf)-1);
     } else
       ftplogprev = 0L;
     debug(F101,"ftp cx log dialog","",dialog);
--- ckuus3.c
+++ ckuus3.c
@@ -4653,8 +4653,8 @@
         cx_prev = t2;
         p = hhmmss(t2);
         debug(F110,"dologend hhmmss",p,0);
-        strncat(cxlogbuf,"E=",CXLOGBUFL); /* Append to log record */
-        strncat(cxlogbuf,p,CXLOGBUFL);
+        strncat(cxlogbuf,"E=",CXLOGBUFL-strlen(cxlogbuf)-1); /* Append to log record */
+        strncat(cxlogbuf,p,CXLOGBUFL-strlen(cxlogbuf)-1);
         debug(F110,"dologend cxlogbuf 2",cxlogbuf,0);
     } else
       cx_prev = 0L;
--- ckuus4.c
+++ ckuus4.c
@@ -8147,8 +8147,8 @@
                 char *p = bp[0];        /* Reuse this space */
                 *p = NUL;               /* Make into dodo() arg list */
                 for (i = 1; i < argn; i++) {
-                    strncat(p,bp[i],MAXARGLEN);
-                    strncat(p," ",MAXARGLEN);
+                    strncat(p,bp[i],MAXARGLEN-strlen(p)-1);
+                    strncat(p," ",MAXARGLEN-strlen(p)-1);
                 }
                 s = bp[0];              /* Point to new list */
             }
--- ckuus7.c
+++ ckuus7.c
@@ -10449,8 +10449,8 @@
                 if ((x = cmtxt("Rest of command","",&s,xxstring)) < 0)
                   return(x);
                 if (*s) {
-                    strncat(line," ",LINBUFSIZ);
-                    strncat(line,s,LINBUFSIZ);
+                    strncat(line," ",LINBUFSIZ-strlen(line)-1);
+                    strncat(line,s,LINBUFSIZ-strlen(line)-1);
                 }
                 s = line;
             }