Classfile compatibility, see Bug 317381
diff --git a/releng/build-scripts/bin/mkotre.sh b/releng/build-scripts/bin/mkotre.sh
index b1d098f..c4e4890 100644
--- a/releng/build-scripts/bin/mkotre.sh
+++ b/releng/build-scripts/bin/mkotre.sh
@@ -21,7 +21,7 @@
 
 # COMPILE
 cd ${ROOT}/OTRE/src
-javac -g -d ../bin -classpath ${BCEL_JAR}:. `find . -name \*.java`
+javac -g -target 1.5 -d ../bin -classpath ${BCEL_JAR}:. `find . -name \*.java`
 
 cd ${ROOT}/OTRE/bin