--- Makefile.orig	2018-04-09 07:59:27.384304829 +0200
+++ Makefile	2018-04-09 07:59:37.612201789 +0200
@@ -27352,7 +27352,7 @@
 
 $(scripts_java_JAVA_CLASSES) : %.class : %.java | scripts/java/$(octave_dirstamp)
 	$(AM_V_GEN)$(MKDIR_P) scripts/java/$(org_octave_dir) && \
-		( cd $(srcdir)/scripts/java; "$(JAVAC)" -source 1.3 -target 1.3 -Xlint:-options -d $(abs_top_builddir)/scripts/java $(org_octave_dir)/$(<F) )
+		( cd $(srcdir)/scripts/java; "$(JAVAC)" -source 1.6 -target 1.6 -Xlint:-options -d $(abs_top_builddir)/scripts/java $(org_octave_dir)/$(<F) )
 
 scripts/java/octave.jar: $(scripts_java_JAVA_CLASSES)
 	$(AM_V_GEN)rm -f address@hidden $@ && \