diff --git a/tests/Android.mk b/tests/Android.mk
index 12fbdc7..5598c2e 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -26,6 +26,10 @@
 
 LOCAL_STATIC_JAVA_LIBRARIES := android-support-test
 
+# For LOCAL_JAVA_LANGUAGE_VERSION >= 1.7, OpenJDK 9 javac generates synthetic calls to
+# Objects.requireNonNull() which was only added in Android API level 19. Thus, this must
+# stay at 1.6 as long as LOCAL_SDK_VERSION is set to a value < 19. See http://b/38495704
+LOCAL_JAVA_LANGUAGE_VERSION := 1.6
 LOCAL_SDK_VERSION := 14
 LOCAL_PACKAGE_NAME := EmailTests
 LOCAL_INSTRUMENTATION_FOR := Email