diff --git a/xCAT/postscripts/configib b/xCAT/postscripts/configib
index 1bbf7e734..8664f6626 100755
--- a/xCAT/postscripts/configib
+++ b/xCAT/postscripts/configib
@@ -19,7 +19,7 @@
 
 #This is the number of ports for each ib adpator.
 portnum=1
-if [ -n "NIC_IBAPORTS" ]; then
+if [ -n "$NIC_IBAPORTS" ]; then
     portnum=$NIC_IBAPORTS
 fi