diff --git a/README.md b/README.md
index 9088421..69e1537 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,7 @@ The final classes and methods in the following libraries cannot be mocked.
 - [Dexmaker](https://github.com/linkedin/dexmaker)
 - [DexMockito](https://github.com/tmurakami/dexmockito)
 - DexOpener
+- [Mockito4k](https://github.com/tmurakami/mockito4k)
 - [Hamcrest](https://github.com/hamcrest/JavaHamcrest)
 - [JUnit](http://junit.org/)
 - [Kotlin](https://kotlinlang.org/)
diff --git a/src/main/java/com/github/tmurakami/dexopener/BuiltinClassNameFilter.java b/src/main/java/com/github/tmurakami/dexopener/BuiltinClassNameFilter.java
index 23876d8..9c6af9a 100644
--- a/src/main/java/com/github/tmurakami/dexopener/BuiltinClassNameFilter.java
+++ b/src/main/java/com/github/tmurakami/dexopener/BuiltinClassNameFilter.java
@@ -12,6 +12,7 @@ final class BuiltinClassNameFilter implements ClassNameFilter {
             "com.github.tmurakami.classinjector.",
             "com.github.tmurakami.dexmockito.",
             "com.github.tmurakami.dexopener.",
+            "com.github.tmurakami.mockito4k.",
             "java.",
             "javax.",
             "junit.",
diff --git a/src/test/java/com/github/tmurakami/dexopener/BuiltinClassNameFilterTest.java b/src/test/java/com/github/tmurakami/dexopener/BuiltinClassNameFilterTest.java
index 3e6936b..30376db 100644
--- a/src/test/java/com/github/tmurakami/dexopener/BuiltinClassNameFilterTest.java
+++ b/src/test/java/com/github/tmurakami/dexopener/BuiltinClassNameFilterTest.java
@@ -29,6 +29,7 @@ public static Iterable<Object[]> parameters() {
                 new Object[]{"com.github.tmurakami.classinjector.C", false},
                 new Object[]{"com.github.tmurakami.dexmockito.C", false},
                 new Object[]{DexOpener.class.getName(), false},
+                new Object[]{"com.github.tmurakami.mockito4k.C", false},
                 new Object[]{"java.C", false},
                 new Object[]{"javax.C", false},
                 new Object[]{"junit.C", false},