diff -r 80ac5e17772d -r 8f7d802b7a71 Admin/lib/Tools/build_doc
--- a/Admin/lib/Tools/build_doc	Tue Sep 08 15:37:13 2015 +0200
+++ b/Admin/lib/Tools/build_doc	Tue Sep 08 17:34:46 2015 +0200
@@ -4,6 +4,17 @@
 #
 # DESCRIPTION: build Isabelle documentation
 
+## settings
+
+case "$ISABELLE_JAVA_PLATFORM" in
+  x86-*)
+    ISABELLE_BUILD_JAVA_OPTIONS="$ISABELLE_BUILD_JAVA_OPTIONS32"
+    ;;
+  x86_64-*)
+    ISABELLE_BUILD_JAVA_OPTIONS="$ISABELLE_BUILD_JAVA_OPTIONS64"
+    ;;
+esac
+
 
 ## diagnostics