diff -up xterm-308/main.c.Soption xterm-308/main.c
--- xterm-308/main.c.Soption	2015-03-03 14:56:32.694437394 +0100
+++ xterm-308/main.c	2015-03-03 14:58:50.729807609 +0100
@@ -777,7 +777,8 @@ static char etc_wtmp[] = WTMP_FILENAME;
 static char bin_login[] = LOGIN_FILENAME;
 #endif
 
-static char passedPty[PTYCHARLEN + 1];	/* name if pty if slave */
+static char noPassedPty[2];
+static char *passedPty = noPassedPty;  /* name if pty if slave */
 
 #if defined(TIOCCONS) || defined(SRIOCSREDIR)
 static int Console;
@@ -1758,6 +1759,7 @@ ParseSccn(char *option)
     char *leaf = x_basename(option);
     Bool code = False;
 
+    passedPty = x_strdup(option);
     if (leaf != option) {
 	if (leaf - option > 0
 	    && isdigit(CharOf(*leaf))
@@ -1769,13 +1771,13 @@ ParseSccn(char *option)
 	     * the /dev/pts/XXX value, but since we do not need to reopen it,
 	     * it is useful mainly for display in a "ps -ef".
 	     */
-	    strncpy(passedPty, option, len);
 	    passedPty[len] = 0;
 	    code = True;
 	}
     } else {
 	code = (sscanf(option, "%c%c%d",
 		       passedPty, passedPty + 1, &am_slave) == 3);
+	passedPty[2] = '\0';
     }
     TRACE(("ParseSccn(%s) = '%s' %d (%s)\n", option,
 	   passedPty, am_slave, code ? "OK" : "ERR"));