-define([VERSION_STRING], m4_esyscmd_s(git describe 2> /dev/null))
-m4_ifval(VERSION_STRING, [], [define([VERSION_STRING], VERSION_NUMBER[]VERSION_SUFFIX)])
+# We do not use m4_esyscmd_s to support older autoconf.
+define([VERSION_STRING], m4_esyscmd(git describe 2>/dev/null | sed 's/^v//' | tr -d '\n'))
+m4_ifval(VERSION_STRING, [], [define([VERSION_STRING], VERSION_NUMBER)])