Index: VirtualBox-5.1.4/src/VBox/Main/webservice/Makefile.kmk
===================================================================
--- VirtualBox-5.1.4.orig/src/VBox/Main/webservice/Makefile.kmk
+++ VirtualBox-5.1.4/src/VBox/Main/webservice/Makefile.kmk
@@ -724,7 +724,7 @@ $(VBOXWEB_OUT_DIR)/gsoap_generate_all_ts
 		$(RECOMPILE_ON_MAKEFILE_CURRENT) | $$(dir $$@)
 	$(call MSG_GENERATE,,lots of files,$(GSOAPH_RELEVANT))
 	$(RM) -f $@
-	$(REDIRECT) -C $(VBOXWEB_OUT_DIR) -- $(VBOX_SOAPCPP2) $(VBOXWEB_SOAPCPP2_SKIP_FILES) -L -2 -w -I$(VBOX_PATH_GSOAP_IMPORT) $(GSOAPH_RELEVANT)
+	$(REDIRECT) -C $(VBOXWEB_OUT_DIR) -- $(VBOX_SOAPCPP2) $(VBOXWEB_SOAPCPP2_SKIP_FILES) -z1 -L -2 -w -I$(VBOX_PATH_GSOAP_IMPORT) $(GSOAPH_RELEVANT)
 ifeq ($(KBUILD_TARGET),win) # MSC -Wall workaround.
 	$(CP) -f "$(VBOXWEB_SOAP_CLIENT_H)" "$(VBOXWEB_SOAP_CLIENT_H).tmp"
 	$(SED) -f $(VBOX_PATH_WEBSERVICE)/stdsoap2.sed --output "$(VBOXWEB_SOAP_CLIENT_H)" "$(VBOXWEB_SOAP_CLIENT_H).tmp"