diff --git a/src/Makefile.am b/src/Makefile.am
index bcffbf29..7379e265 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -3,10 +3,7 @@
 sbin_PROGRAMS = tincd tinc sptps_test sptps_keypair
 
 ## Make sure version.c is always rebuilt with the latest git information
-.PHONY: ${srcdir}/version.c version_git.h
-version_git.h:
-	echo >$@
-	-(cd $(srcdir) && git describe) && echo '#define GIT_DESCRIPTION "'`(cd $(srcdir) && git describe) | sed 's/release-//'`'"' >$@
+$(eval include version_git.mak)
 ${srcdir}/version.c: version_git.h
 
 if LINUX
diff --git a/src/version_git.mak b/src/version_git.mak
new file mode 100644
index 00000000..f4dfecf8
--- /dev/null
+++ b/src/version_git.mak
@@ -0,0 +1,9 @@
+gitdescription_new=$(shell git describe | sed 's/^release-//')
+gitdescription_old=$(shell sed 's/.*"\(.*\)".*/\1/' version_git.h)
+
+ifneq ($(gitdescription_new), $(gitdescription_old))
+version_git.h:
+	echo $(gitdescription_new)
+	echo $(gitdescription_old)
+	echo '#define GIT_DESCRIPTION "$(gitdescription_new)"' >$@
+endif