diff --git a/build.gradle b/build.gradle
index a7e6285..178e2c7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,6 +1,6 @@
 plugins {
     id 'com.github.johnrengelman.shadow' version '7.1.2'
-    id 'edu.sc.seis.launch4j' version '2.4.6'
+    id 'edu.sc.seis.launch4j' version '2.5.4'
     id 'java'
 }
 
@@ -18,6 +18,9 @@ dependencies {
 }
 
 java {
+    sourceCompatibility JavaVersion.VERSION_1_8
+    targetCompatibility JavaVersion.VERSION_1_8
+
     withSourcesJar()
 }