diff --git a/lib/vty.c b/lib/vty.c
index 750f885..d623b85 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -870,7 +870,7 @@
 
   /* In case of 'help \t'. */
   if (isspace ((int) vty->buf[vty->length - 1]))
-    vector_set (vline, '\0');
+    vector_set (vline, NULL);
 
   matched = cmd_complete_command (vline, vty, &ret);
   
@@ -985,11 +985,11 @@
   if (vline == NULL)
     {
       vline = vector_init (1);
-      vector_set (vline, '\0');
+      vector_set (vline, NULL);
     }
   else 
     if (isspace ((int) vty->buf[vty->length - 1]))
-      vector_set (vline, '\0');
+      vector_set (vline, NULL);
 
   describe = cmd_describe_command (vline, vty, &ret);
 
diff --git a/vtysh/vtysh.c b/vtysh/vtysh.c
index 984f8d3..5490b33 100644
--- a/vtysh/vtysh.c
+++ b/vtysh/vtysh.c
@@ -563,11 +563,11 @@
   if (vline == NULL)
     {
       vline = vector_init (1);
-      vector_set (vline, '\0');
+      vector_set (vline, NULL);
     }
   else 
     if (rl_end && isspace ((int) rl_line_buffer[rl_end - 1]))
-      vector_set (vline, '\0');
+      vector_set (vline, NULL);
 
   describe = cmd_describe_command (vline, vty, &ret);
 
@@ -657,7 +657,7 @@
 	return NULL;
 
       if (rl_end && isspace ((int) rl_line_buffer[rl_end - 1]))
-	vector_set (vline, '\0');
+        vector_set (vline, NULL);
 
       matched = cmd_complete_command (vline, vty, &complete_status);
     }