diff --git a/tests/script/general/parser/alter.sim b/tests/script/general/parser/alter.sim
index e57b1f43d28363a146b2e18b694adc4be88370c8..44c12fa968d52b7c6e3811d4997e549af3bba7bf 100644
--- a/tests/script/general/parser/alter.sim
+++ b/tests/script/general/parser/alter.sim
@@ -38,7 +38,7 @@ endi
 if $data02 != 1 then 
   return -1
 endi
-if $data03 != NULL then
+if $data03 != null then
   return -1
 endi
 sql alter table tb add column c3 nchar(4)
@@ -72,7 +72,7 @@ endi
 if $data02 != 1 then 
   return -1
 endi
-if $data03 != NULL then
+if $data03 != null then
   return -1
 endi
 
@@ -169,7 +169,7 @@ endi
 if $data01 != 2 then
   return -1
 endi
-if $data02 != NULL then
+if $data02 != null then
   return -1
 endi
 sql alter table mt add column c2 int
@@ -239,4 +239,4 @@ if $rows != 0 then
   return -1
 endi
 
-system sh/exec.sh -n dnode1 -s stop -x SIGINT
\ No newline at end of file
+system sh/exec.sh -n dnode1 -s stop -x SIGINT