diff --git a/infer/annotations/com/facebook/infer/annotation/OkToExtend.java b/infer/annotations/com/facebook/infer/annotation/OkToExtend.java
new file mode 100644
index 000000000..b0de58229
--- /dev/null
+++ b/infer/annotations/com/facebook/infer/annotation/OkToExtend.java
@@ -0,0 +1,19 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+package com.facebook.infer.annotation;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Marks a class as one that is expected to be extended.
+ *
+ * This annotation is meant to counter common misuses of subclassing. Annotate your class with this
+ * only if it was built with the purpose of being extended.
+ *
+ * Avoid adding this to classes that have existed for a long time without needing it.
+ */
+@Retention(RetentionPolicy.SOURCE)
+public @interface OkToExtend {
+
+}