diff --git a/build.gradle b/build.gradle
index 43748db88579aab3cac0cb3a86f252e11377166b..887cd9ff5e09a680837b4299513ccb66ce7c8358 100644
--- a/build.gradle
+++ b/build.gradle
@@ -81,6 +81,7 @@ jar {
     from {
         configurations.runtimeClasspath.collect { return (it.isDirectory() ? it : zipTree(it)) }
     }
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 }
 
 def relastFiles = ['./src/main/jastadd/common/MotionGrammar.relast', './src/main/jastadd/World.relast', './src/main/jastadd/LoadUnload.relast']