diff --git a/changelog.txt b/changelog.txt
index 0b020966..f73d2e36 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -14,6 +14,7 @@ Whenever you upgrade code pal for ABAP, it is highly recommended to execute the
 
 2021-04-** v.1.14.0
 ------------------
+* Standard functions in Prefer IS NOT to NOT IS (#338)
 * In the profile feature, you can add all the missing checks (#346)
 
 2021-04-05 v.1.13.1
diff --git a/src/checks/y_check_prefer_is_not.clas.abap b/src/checks/y_check_prefer_is_not.clas.abap
index ea4b6bf9..163a8fa8 100644
--- a/src/checks/y_check_prefer_is_not.clas.abap
+++ b/src/checks/y_check_prefer_is_not.clas.abap
@@ -5,6 +5,9 @@ CLASS y_check_prefer_is_not DEFINITION PUBLIC INHERITING FROM y_check_base CREAT
   PROTECTED SECTION.
     METHODS inspect_tokens REDEFINITION.
 
+    METHODS is_standard_function IMPORTING token TYPE stokesx
+                                 RETURNING VALUE(result) TYPE abap_bool.
+
 ENDCLASS.
 
 
@@ -33,7 +36,8 @@ CLASS y_check_prefer_is_not IMPLEMENTATION.
     WHERE str = 'IF'
     OR str = 'ELSEIF'
     OR str = 'AND'
-    OR str = 'OR'.
+    OR str = 'OR'
+    OR str = 'ASSERT'.
 
       DATA(position) = sy-tabix.
 
@@ -46,7 +50,7 @@ CLASS y_check_prefer_is_not IMPLEMENTATION.
       ENDTRY.
 
       TRY.
-          IF ref_scan_manager->tokens[ position + 2 ]-str = 'LINE_EXISTS('.
+          IF is_standard_function( ref_scan_manager->tokens[ position + 2 ] ) = abap_true.
             CONTINUE.
           ENDIF.
         CATCH cx_sy_itab_line_not_found.
@@ -67,4 +71,12 @@ CLASS y_check_prefer_is_not IMPLEMENTATION.
     ENDLOOP.
   ENDMETHOD.
 
+
+  METHOD is_standard_function.
+    result = xsdbool(    token-str CP 'CONTAINS*'
+                      OR token-str CP 'LINE_EXISTS*'
+                      OR token-str CP 'MATCHES*' ).
+  ENDMETHOD.
+
+
 ENDCLASS.
diff --git a/src/checks/y_check_prefer_is_not.clas.testclasses.abap b/src/checks/y_check_prefer_is_not.clas.testclasses.abap
index f9bdb0aa..4b1e42eb 100644
--- a/src/checks/y_check_prefer_is_not.clas.testclasses.abap
+++ b/src/checks/y_check_prefer_is_not.clas.testclasses.abap
@@ -342,8 +342,84 @@ CLASS ltc_line_exists IMPLEMENTATION.
 
       ( ' START-OF-SELECTION. ' )
       ( '   DATA itab TYPE TABLE OF tadir. ' )
-      ( '   IF NOT line_exists( itab[ 0 ] ). ' )
-      ( '   ENDIF. ' )
+      ( '   ASSERT NOT line_exists( itab[ 0 ] ). ' )
+    ).
+  ENDMETHOD.
+
+ENDCLASS.
+
+
+
+CLASS ltc_contains DEFINITION INHERITING FROM ltc_not_value FOR TESTING RISK LEVEL HARMLESS DURATION SHORT.
+  PROTECTED SECTION.
+    METHODS get_code_without_issue REDEFINITION.
+ENDCLASS.
+
+CLASS ltc_contains IMPLEMENTATION.
+
+  METHOD get_code_without_issue.
+    result = VALUE #(
+      ( 'REPORT y_example. ' )
+
+      ( ' START-OF-SELECTION. ' )
+      ( |   ASSERT NOT contains( val = 'code pal for ABAP' sub = 'ABAP' ). | )
+    ).
+  ENDMETHOD.
+
+ENDCLASS.
+
+
+CLASS ltc_matches DEFINITION INHERITING FROM ltc_not_value FOR TESTING RISK LEVEL HARMLESS DURATION SHORT.
+  PROTECTED SECTION.
+    METHODS get_code_without_issue REDEFINITION.
+ENDCLASS.
+
+CLASS ltc_matches IMPLEMENTATION.
+
+  METHOD get_code_without_issue.
+    result = VALUE #(
+      ( ' REPORT y_example. ' )
+
+      ( ' START-OF-SELECTION. ' )
+      ( |   ASSERT NOT matches( val = 'a123e' regex = '[[:alpha:]]*' ). | )
+    ).
+  ENDMETHOD.
+
+ENDCLASS.
+
+
+CLASS ltc_contains_any_not_of DEFINITION INHERITING FROM ltc_not_value FOR TESTING RISK LEVEL HARMLESS DURATION SHORT.
+  PROTECTED SECTION.
+    METHODS get_code_without_issue REDEFINITION.
+ENDCLASS.
+
+CLASS ltc_contains_any_not_of IMPLEMENTATION.
+
+  METHOD get_code_without_issue.
+    result = VALUE #(
+      ( ' REPORT y_example. ' )
+
+      ( ' START-OF-SELECTION. ' )
+      ( |   ASSERT NOT contains_any_not_of( val = 'a123e' sub = '123' ). | )
+    ).
+  ENDMETHOD.
+
+ENDCLASS.
+
+
+CLASS ltc_contains_any_of DEFINITION INHERITING FROM ltc_not_value FOR TESTING RISK LEVEL HARMLESS DURATION SHORT.
+  PROTECTED SECTION.
+    METHODS get_code_without_issue REDEFINITION.
+ENDCLASS.
+
+CLASS ltc_contains_any_of IMPLEMENTATION.
+
+  METHOD get_code_without_issue.
+    result = VALUE #(
+      ( ' REPORT y_example. ' )
+
+      ( ' START-OF-SELECTION. ' )
+      ( |   ASSERT NOT contains_any_of( val = 'a123e' sub = '123' ). | )
     ).
   ENDMETHOD.