diff --git a/build.gradle b/build.gradle
index 3973a620..92d45030 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,3 +1,8 @@
+// all projects must be comatible with the java version specified here
+// overriding this property in subprojects is not allowed
+sourceCompatibility = '1.8'
+[compileJava, compileTestJava]*.options*.encoding = 'UTF-8'
+
 task wrapper(type: Wrapper) {
     gradleVersion = '1.11'
 }