diff --git a/core/java/android/util/LruCache.java b/core/java/android/util/LruCache.java
index 5540000eff434..f1014a7ae1b19 100644
--- a/core/java/android/util/LruCache.java
+++ b/core/java/android/util/LruCache.java
@@ -54,6 +54,10 @@ import java.util.Map;
  * <p>This class does not allow null to be used as a key or value. A return
  * value of null from {@link #get}, {@link #put} or {@link #remove} is
  * unambiguous: the key was not in the cache.
+ *
+ * <p>This class appeared in Android 3.1 (Honeycomb MR1); it's available as part
+ * of <a href="http://developer.android.com/sdk/compatibility-library.html">Android's
+ * Support Package</a> for earlier releases.
  */
 public class LruCache<K, V> {
     private final LinkedHashMap<K, V> map;