diff --git a/OpenKeychain/build.gradle b/OpenKeychain/build.gradle
index 9d8469144..05b9bd73e 100644
--- a/OpenKeychain/build.gradle
+++ b/OpenKeychain/build.gradle
@@ -37,6 +37,11 @@ android {
         targetSdkVersion 21
     }
 
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_7
+        targetCompatibility JavaVersion.VERSION_1_7
+    }
+
     /*
      * To sign release build, create file gradle.properties in ~/.gradle/ with this content:
      *