diff --git a/bsf.spec b/bsf.spec
index 5c7f41f..6910986 100644
--- a/bsf.spec
+++ b/bsf.spec
@@ -93,7 +93,7 @@ rm -fr bsf
 %build
 mkdir -p lib
 build-jar-repository -s -p lib apache-commons-logging rhino xalan-j2
-%{ant} jar javadocs
+%{ant} -Dant.build.javac.source=1.6 -Dant.build.javac.target=1.6 jar javadocs
 
 %install
 # jar