diff --git a/README.md b/README.md
index 0b1d1a7..2598dd6 100644
--- a/README.md
+++ b/README.md
@@ -1197,16 +1197,23 @@ Checks that labels are not used.
 
 #### [IllegalType](http://checkstyle.sourceforge.net/config_coding.html#IllegalType)
 
-Prevents variables, parameters and method returns from being one of the following:
+Prevents use of implementation classes as variables, parameters or method returns. Use the interfaces instead.
 
-* java.util.HashSet
+Prevents variables, parameters and method returns from being any of the following:
+
+* java.util.ArrayDeque
+* java.util.ArrayList
+* java.util.EnumMap
+* java.util.EnumSet
 * java.util.HashMap
+* java.util.HashSet
+* java.util.IdentityHashMap
 * java.util.LinkedHashMap
 * java.util.LinkedHashSet
-* java.util.TreeSet
+* java.util.LinkedList
+* java.util.PriorityQueue
 * java.util.TreeMap
-
-> TODO: add more classes from Collections
+* java.util.TreeSet
 
 Valid:
 ````
diff --git a/src/main/resources/net/kemitix/checkstyle.xml b/src/main/resources/net/kemitix/checkstyle.xml
index 520c9f2..bc75507 100644
--- a/src/main/resources/net/kemitix/checkstyle.xml
+++ b/src/main/resources/net/kemitix/checkstyle.xml
@@ -100,7 +100,9 @@
         <module name="IllegalImport"/> <!-- prevent imports from the sun.* package -->
         <module name="IllegalThrows"/> <!-- prevent generic throws (i.e. Exception, Throwable, RuntimeException) -->
         <module name="IllegalToken"/> <!-- prevents use of labels -->
-        <module name="IllegalType"/> <!-- prevents variables, returns or parameters of non-interface Collections classes  -->
+        <module name="IllegalType"> <!-- prevents variables, returns or parameters of non-interface Collections classes  -->
+            <property name="illegalClassNames" value="java.util.ArrayDeque, java.util.ArrayList, java.util.EnumMap, java.util.EnumSet, java.util.HashMap, java.util.HashSet, java.util.IdentityHashMap, java.util.LinkedHashMap, java.util.LinkedHashSet, java.util.LinkedList, java.util.PriorityQueue, java.util.TreeMap, java.util.TreeSet"/>
+        </module>
         <module name="InnerAssignment"/> <!-- prevent assignments in subexpressions (i.e. while((line = read()){}) -->
         <module name="InnerTypeLast"/> <!-- inner classes appear after methods and fields -->
         <module name="InterfaceIsType"/> <!-- interface must define method not just constants -->