PKG_INSTALL_DIR ?= $(PKG_BUILD_DIR)/ipkg-install
PKG_MD5SUM ?= unknown
PKG_BUILD_PARALLEL ?=
-PKG_JOBS ?= $(if $(PKG_BUILD_PARALLEL)$(CONFIG_PKG_DEFAULT_PARALLEL),$(if $(CONFIG_PKG_BUILD_PARALLEL),-j$(CONFIG_PKG_BUILD_JOBS)))
+
+ifeq ($(strip $(PKG_BUILD_PARALLEL)),0)
+PKG_JOBS?=-j1
+else
+PKG_JOBS?=$(if $(PKG_BUILD_PARALLEL)$(CONFIG_PKG_DEFAULT_PARALLEL),\
+ $(if $(CONFIG_PKG_BUILD_PARALLEL),-j$(CONFIG_PKG_BUILD_JOBS),-j1),-j1)
+endif
include $(INCLUDE_DIR)/prereq.mk
include $(INCLUDE_DIR)/host.mk