diff --git a/tools/Makefile.am b/tools/Makefile.am
index d639c94d8..bb5a61a76 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -64,19 +64,21 @@ dirs:
 	  $(MKDIR_P) $$subdir || exit 1; \
 	  done
 
-hotplug/libsane.usermap: $(wildcard ${top_srcdir}/doc/descriptions/*.desc) $(wildcard ${top_srcdir}/doc/descriptions-external/*.desc) sane-desc
+descriptions = ${top_srcdir}/doc/descriptions/*.desc ${top_srcdir}/doc/descriptions-external/*.desc
+
+hotplug/libsane.usermap: sane-desc $(descriptions)
 	@./sane-desc -m usermap -s ${top_srcdir}/doc/descriptions:${top_srcdir}/doc/descriptions-external \
 	   -d 1 > $@
 
-hotplug-ng/libsane.db: $(wildcard ${top_srcdir}/doc/descriptions/*.desc) $(wildcard ${top_srcdir}/doc/descriptions-external/*.desc) sane-desc
+hotplug-ng/libsane.db: sane-desc $(descriptions)
 	@./sane-desc -m db -s ${top_srcdir}/doc/descriptions:${top_srcdir}/doc/descriptions-external \
 	   -d 0 > $@
 
-udev/libsane.rules: $(wildcard ${top_srcdir}/doc/descriptions/*.desc) $(wildcard ${top_srcdir}/doc/descriptions-external/*.desc) sane-desc
+udev/libsane.rules: sane-desc $(descriptions)
 	@./sane-desc -m udev -s ${top_srcdir}/doc/descriptions:${top_srcdir}/doc/descriptions-external \
 	   -d 0 > $@
 
-hal/libsane.fdi: $(wildcard ${top_srcdir}/doc/descriptions/*.desc) $(wildcard ${top_srcdir}/doc/descriptions-external/*.desc) sane-desc
+hal/libsane.fdi: sane-desc $(descriptions)
 	@./sane-desc -m hal -s ${top_srcdir}/doc/descriptions:${top_srcdir}/doc/descriptions-external \
 	   -d 0 > $@