diff --git a/ChangeLog b/ChangeLog
index fdb0a8ba69..7dd34c0047 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Feb 10 21:58:32 2008  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* common.mk (encdb, transdb): depend on $(PREP).
+
 Sun Feb 10 16:58:20 2008  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/rubygems*, test/rubygems*, gem_prelude.rb: Import RubyGems
diff --git a/common.mk b/common.mk
index f737d6bae5..b4f4b9dc2e 100644
--- a/common.mk
+++ b/common.mk
@@ -707,14 +707,14 @@ incs: $(INSNS) {$(VPATH)}node_name.inc {$(VPATH)}encdb.h {$(VPATH)}transdb.h $(s
 node_name.inc: {$(VPATH)}node.h
 	$(BASERUBY) -n $(srcdir)/tool/node_name.rb $? > $@
 
-encdb:
+encdb: $(PREP)
 	$(MINIRUBY) $(srcdir)/enc/make_encdb.rb $(srcdir)/enc encdb.h.new
 	$(IFCHANGE) "encdb.h" "encdb.h.new"
 
 encdb.h:
 	$(MINIRUBY) $(srcdir)/enc/make_encdb.rb $(srcdir)/enc $@
 
-transdb:
+transdb: $(PREP)
 	$(MINIRUBY) $(srcdir)/enc/trans/make_transdb.rb $(srcdir)/enc/trans transdb.h.new
 	$(IFCHANGE) "transdb.h" "transdb.h.new"