diff --git a/RELEASES.md b/RELEASES.md
index 25e9dd39..f0caaec5 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -13,6 +13,18 @@ TAME developers: Add new changes under a "NEXT" heading as part of the
 commits that introduce the changes.  To make a new release, run
 `tools/mkrelease`, which will handle updating the heading for you.
 
+NEXT
+====
+This release contains changes to the build system to accommodate
+liza-proguic's introduction of step-based packages (in place of a monolithic
+`package-dfns.xml`), as well as miscellaneous improvements.
+
+Build System
+------------
+- Only modify `.version.xml` timestamp when hash changes.  This allows
+  its use as a dependency without forcefully rebuilding each and every time.
+
+
 v17.7.0 (2020-12-09)
 ====================
 This release provides tail-call optimizations aimed at the query system in
diff --git a/build-aux/Makefile.am b/build-aux/Makefile.am
index a0f0be13..5482c3f9 100644
--- a/build-aux/Makefile.am
+++ b/build-aux/Makefile.am
@@ -190,9 +190,14 @@ c1map: $(dest_c1map)
 %.xml: %.csvo rater/core/vector/table.xmlo
 	rater/tools/csv2xml $< > $@
 
+# This target is always run, but only update the file (and thus its
+# timestamp) if the hash actually changes, so that we do not rebuild any
+# dependencies unnecessarily.
 version: .version.xml
 .version.xml: FORCE
-	git log HEAD^.. -1 --pretty=format:'<version>%h</version>' > .version.xml
+	git log HEAD^.. -1 --pretty=format:'<version>%h</version>' > $@.new
+	cmp $@ $@.new || mv $@.new $@
+	$(RM) $@.new
 
 ui/program.expanded.xml: ui/program.xml $(program_fragments)
 	$(TAME_TS)