diff --git a/.gitignore b/.gitignore
index 917b01bc9c..af2a670aeb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ version.ent
 blfs-bootscripts*
 xxx
 *.swp
+build-env
diff --git a/Makefile b/Makefile
index fca84c630f..5841d1f58f 100644
--- a/Makefile
+++ b/Makefile
@@ -34,12 +34,6 @@ ifneq ($(REV), sysv)
   endif
 endif
 
-# Let's get the previous REV: it'll be used to see if we should
-# rebuild version.ent
-PREVREV != if [ -f conditional.ent ]; then \
-              gawk '/INCLUDE/{ print $$3 }' conditional.ent; \
-           fi
-
 ifeq ($(REV), sysv)
   BASEDIR         ?= $(HOME)/public_html/blfs-book
   NOCHUNKS_OUTPUT ?= blfs-book.html
@@ -279,12 +273,7 @@ $(DUMPDIR): $(RENDERTMP)/$(BLFSFULL)
    validate profile-html blfs-patch-list wget-list \
 	test-links dump-commands  bootscripts systemd-units
 
-# make version.ent unconditionally if we have changed REV
-ifneq ($(REV), $(PREVREV))
-   .PHONY: version.ent
-endif
-
-version.ent: general.ent packages.ent gnome.ent $(ALLXML) $(ALLXSL)
+version.ent: general.ent packages.ent gnome.ent $(ALLXML) $(ALLXSL) build-env
 	$(Q)./git-version.sh $(REV)
 
 #ALL_PYTHON_DEPS := $(filter-out $(PYHOSTED), \
@@ -309,3 +298,12 @@ version.ent: general.ent packages.ent gnome.ent $(ALLXML) $(ALLXSL)
 #                stylesheets/pythonhosted.xsl                  \
 #                general/prog/python-modules.xml
 #	$(Q)mv temp.xml $@
+
+.PHONY: update-build-env
+update-build-env:
+	$(Q)echo REV=$(REV) > $@.new
+	$(Q)echo BASEDIR=$(BASEDIR) >> $@.new
+	$(Q)diff $@.new $@ 2>/dev/null >/dev/null || mv $@.new $@
+	$(Q)rm -f $@.new
+
+build-env: update-build-env