diff --git a/abaplint.json b/abaplint.json
index b3310fe..d1b372b 100644
--- a/abaplint.json
+++ b/abaplint.json
@@ -19,6 +19,11 @@
     "globalMacros": []
   },
   "rules": {
+    "constant_classes": true,
+    "cyclic_oo": false,
+    "many_parentheses": true,
+    "pragma_placement": true,
+    "unused_ddic": false,
     "dangerous_statement": true,
     "db_operation_in_loop": false,
     "identical_descriptions": false,
@@ -37,7 +42,6 @@
     "call_transaction_authority_check": true,
     "function_module_recommendations": false,
     "identical_contents": false,
-    "many_parenthesis": false,
     "method_overwrites_builtin": true,
     "omit_parameter_name": false,
     "omit_receiving": true,
diff --git a/src/demos/zdemo_calendar_classes.prog.abap b/src/demos/zdemo_calendar_classes.prog.abap
index fc36bb7..a0a4d4e 100644
--- a/src/demos/zdemo_calendar_classes.prog.abap
+++ b/src/demos/zdemo_calendar_classes.prog.abap
@@ -41,8 +41,7 @@ CLASS zcl_date_calculation IMPLEMENTATION.
 
     e_month = 0.
 
-    CHECK NOT ( i_date_from IS INITIAL )
-      AND NOT ( i_date_to IS INITIAL ).
+    CHECK i_date_from IS NOT INITIAL AND i_date_to IS NOT INITIAL.
 
     date_to = i_date_to.
     IF i_incl_to = abap_true.
@@ -474,4 +473,4 @@ CLASS zcl_helper IMPLEMENTATION.
         ip_style     = i_style
     ).
   ENDMETHOD.                    "add_calender_week
-ENDCLASS.                    "zcl_helper IMPLEMENTATION
+ENDCLASS.                    "zcl_helper IMPLEMENTATION
\ No newline at end of file