diff --git a/build.gradle b/build.gradle
index 90a3eeae..4d8ec599 100644
--- a/build.gradle
+++ b/build.gradle
@@ -9,6 +9,19 @@ subprojects {
 
     compileGroovy {
         groovyOptions.optimizationOptions.indy = true
+        sourceCompatibility = project.sourceCompatibility
+        targetCompatibility = project.targetCompatibility
+        options.compilerArgs += project.compilerArgs
+        options.deprecation = true
+        options.encoding = 'UTF-8'
+    }
+
+    compileJava {
+        sourceCompatibility = project.sourceCompatibility
+        targetCompatibility = project.targetCompatibility
+        options.compilerArgs += project.compilerArgs
+        options.deprecation = true
+        options.encoding = 'UTF-8'
     }
 
     repositories {
diff --git a/core/src/main/java/com/muwire/core/util/DataUtil.java b/core/src/main/java/com/muwire/core/util/DataUtil.java
index 29e288f6..9371d697 100644
--- a/core/src/main/java/com/muwire/core/util/DataUtil.java
+++ b/core/src/main/java/com/muwire/core/util/DataUtil.java
@@ -58,9 +58,9 @@ public class DataUtil {
         if (header.length != 3)
             throw new IllegalArgumentException("header length $header.length");
 
-        return (((int)(header[0] & 0x7F)) << 16) |
-                (((int)(header[1] & 0xFF) << 8)) |
-                ((int)header[2] & 0xFF);
+        return ((header[0] & 0x7F) << 16) |
+                ((header[1] & 0xFF) << 8) |
+                (header[2] & 0xFF);
     }
 
     public static String readi18nString(byte [] encoded) {
@@ -174,7 +174,7 @@ public class DataUtil {
                 clean.setAccessible(true);
                 clean.invoke(cleaner.invoke(cb));
             } else {
-                Class unsafeClass;
+                Class<?> unsafeClass;
                 try {
                     unsafeClass = Class.forName("sun.misc.Unsafe");
                 } catch(Exception ex) {
diff --git a/gradle.properties b/gradle.properties
index 45c6ca75..ec9b57c0 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -8,8 +8,10 @@ grailsVersion=4.0.0
 gorm.version=7.0.2.RELEASE
 griffonEnv=prod
 
+# javac properties
 sourceCompatibility=1.8
 targetCompatibility=1.8
+compilerArgs=-Xlint:unchecked,cast,path,divzero,empty,path,finally,overrides
 
 # plugin properties
 author = zab@mail.i2p