diff --git a/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyCollection.java b/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyCollection.java
index d566d75..c526965 100644
--- a/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyCollection.java
+++ b/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyCollection.java
@@ -33,7 +33,7 @@
  * @author Georgy Vlasov (suseika@tendiwa.org)
  * @version $Id$
  */
-final class WrappingReadOnlyCollection<T> implements ReadOnlyCollection<T> {
+class WrappingReadOnlyCollection<T> implements ReadOnlyCollection<T> {
     /**
      * Wrapped collection.
      */
@@ -49,22 +49,22 @@ public WrappingReadOnlyCollection(final Collection<T> wrp) {
     }
 
     @Override
-    public boolean contains(final T element) {
+    public final boolean contains(final T element) {
         return this.wrapped.contains(element);
     }
 
     @Override
-    public int size() {
+    public final int size() {
         return this.wrapped.size();
     }
 
     @Override
-    public Iterator<T> iterator() {
+    public final Iterator<T> iterator() {
         return this.wrapped.iterator();
     }
 
     @Override
-    public Stream<T> stream() {
+    public final Stream<T> stream() {
         return this.wrapped.stream();
     }
 }
diff --git a/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyList.java b/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyList.java
index 4b6f8a4..0db7c40 100644
--- a/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyList.java
+++ b/src/main/java/org/tendiwa/rocollections/WrappingReadOnlyList.java
@@ -33,7 +33,7 @@
  * @author Georgy Vlasov (suseika@tendiwa.org)
  * @version $Id$
  */
-public final class WrappingReadOnlyList<T> implements ReadOnlyList<T> {
+public class WrappingReadOnlyList<T> implements ReadOnlyList<T> {
     /**
      * Wrapped list.
      */
@@ -49,27 +49,27 @@ public WrappingReadOnlyList(final List<T> wrp) {
     }
 
     @Override
-    public T get(final int index) {
+    public final T get(final int index) {
         return this.wrapped.get(index);
     }
 
     @Override
-    public boolean contains(final T element) {
+    public final boolean contains(final T element) {
         return this.wrapped.contains(element);
     }
 
     @Override
-    public int size() {
+    public final int size() {
         return this.wrapped.size();
     }
 
     @Override
-    public Iterator<T> iterator() {
+    public final Iterator<T> iterator() {
         return this.wrapped.iterator();
     }
 
     @Override
-    public Stream<T> stream() {
+    public final Stream<T> stream() {
         return this.wrapped.stream();
     }
 }
diff --git a/src/main/java/org/tendiwa/rocollections/WrappingReadOnlySet.java b/src/main/java/org/tendiwa/rocollections/WrappingReadOnlySet.java
index a903b80..8e3bf1f 100644
--- a/src/main/java/org/tendiwa/rocollections/WrappingReadOnlySet.java
+++ b/src/main/java/org/tendiwa/rocollections/WrappingReadOnlySet.java
@@ -35,11 +35,11 @@
  * @version $Id$
  */
 @SuppressWarnings("unused")
-public final class WrappingReadOnlySet<T> implements ReadOnlySet<T> {
+public class WrappingReadOnlySet<T> implements ReadOnlySet<T> {
     /**
      * The wrapped Set instance.
      */
-    private final transient Set<T> set;
+    private final Set<T> set;
 
     /**
      * Wraps a {@link java.util.Set}.
@@ -51,7 +51,7 @@ public final class WrappingReadOnlySet<T> implements ReadOnlySet<T> {
     }
 
     @Override
-    public boolean contains(final T element) {
+    public final boolean contains(final T element) {
         return this.set.contains(element);
     }
 
@@ -61,7 +61,7 @@ public boolean contains(final T element) {
      * @return Size of this set.
      */
     @Override
-    public int size() {
+    public final int size() {
         return this.set.size();
     }
 
@@ -71,7 +71,7 @@ public int size() {
      * @return Iterator over elements of this set.
      */
     @Override
-    public Iterator<T> iterator() {
+    public final Iterator<T> iterator() {
         return this.set.iterator();
     }
 
@@ -81,7 +81,7 @@ public Iterator<T> iterator() {
      * @return Stream over elements of this set.
      */
     @Override
-    public Stream<T> stream() {
+    public final Stream<T> stream() {
         return this.set.stream();
     }
 }