diff --git a/Android.mk b/Android.mk
index f3eb679..e5da4a1 100644
--- a/Android.mk
+++ b/Android.mk
@@ -22,5 +22,7 @@
     $(call all-java-files-under,src) \
     $(call all-java-files-under,android)
 
+LOCAL_SDK_VERSION := 21
+
 LOCAL_MODULE_TAGS := optional
 include $(BUILD_JAVA_LIBRARY)