diff --git a/xz-java.spec b/xz-java.spec
index 9a34980..252c25e 100644
--- a/xz-java.spec
+++ b/xz-java.spec
@@ -35,7 +35,7 @@ This package contains the API documentation for %{name}.
 # package-list from oracle.com. Create a dummy package-list to prevent that.
 mkdir -p extdoc && touch extdoc/package-list
 
-ant maven
+ant maven -Dsourcever=1.6
 
 %install
 %mvn_artifact build/maven/xz-%{version}.pom build/jar/xz.jar