diff --git a/ChangeLog b/ChangeLog
index 59a3e016f5..b2f46a05b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri May 30 12:18:43 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* common.mk (prelude.c): simply depends on PREP.  [ruby-dev:34877]
+
+	* enc/make_encdb.rb, enc/trans/make_transdb.rb: ditto.
+
 Fri May 30 10:55:42 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* vm_core.h (struct rb_unblock_callback), thread.c
diff --git a/Makefile.in b/Makefile.in
index 5aa12a8fa7..bd90cd4f77 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -204,5 +204,3 @@ distclean-local::
 
 ext/extinit.$(OBJEXT): ext/extinit.c $(SETUP)
 	$(CC) $(CFLAGS) $(XCFLAGS) $(CPPFLAGS) $(COUTFLAG)$@ -c ext/extinit.c
-
-MKPREP = $(PREP) $(RBCONFIG)
diff --git a/common.mk b/common.mk
index d58521229d..3f6986e40d 100644
--- a/common.mk
+++ b/common.mk
@@ -109,6 +109,8 @@ TESTWORKDIR   = testwork
 
 BOOTSTRAPRUBY = $(BASERUBY)
 
+COMPILE_PRELUDE = $(MINIRUBY) -I$(srcdir) -rrbconfig $(srcdir)/tool/compile_prelude.rb
+
 VCS           = svn
 
 all: $(MKFILES) incs $(PREP) $(RBCONFIG) $(LIBRUBY) encs
@@ -377,7 +379,7 @@ encs: enc.mk $(LIBRUBY)
 	$(MAKE) -f enc.mk $(MFLAGS)
 
 enc.mk: $(srcdir)/enc/make_encmake.rb $(srcdir)/enc/Makefile.in $(srcdir)/enc/depend \
-	$(srcdir)/lib/mkmf.rb $(MKPREP)
+	$(srcdir)/lib/mkmf.rb $(PREP)
 	$(MINIRUBY) $(srcdir)/enc/make_encmake.rb --builtin-encs="$(BUILTIN_ENCOBJS)" $@
 
 .PRECIOUS: $(MKFILES)
@@ -742,14 +744,11 @@ transdb.h: $(PREP)
 miniprelude.c: $(srcdir)/tool/compile_prelude.rb $(srcdir)/prelude.rb
 	$(BASERUBY) -I$(srcdir) $(srcdir)/tool/compile_prelude.rb $(srcdir)/prelude.rb $@
 
-prelude.c: $(srcdir)/tool/compile_prelude.rb $(PRELUDE_SCRIPTS) $(MKPREP)
-	$(MINIRUBY) -I$(srcdir) -rrbconfig $(srcdir)/tool/compile_prelude.rb \
-		$(PRELUDE_SCRIPTS) $@.new
-	$(IFCHANGE) "$@" "$@.new"
+prelude.c: $(srcdir)/tool/compile_prelude.rb $(PRELUDE_SCRIPTS) $(PREP)
+	$(COMPILE_PRELUDE) $(PRELUDE_SCRIPTS) $@
 
-golf_prelude.c: $(srcdir)/tool/compile_prelude.rb $(srcdir)/prelude.rb $(srcdir)/golf_prelude.rb $(MKPREP)
-	$(MINIRUBY) -I$(srcdir) -rrbconfig $(srcdir)/tool/compile_prelude.rb $(srcdir)/golf_prelude.rb $@.new
-	$(IFCHANGE) "$@" "$@.new"
+golf_prelude.c: $(srcdir)/tool/compile_prelude.rb $(srcdir)/prelude.rb $(srcdir)/golf_prelude.rb $(PREP)
+	$(COMPILE_PRELUDE) $(srcdir)/golf_prelude.rb $@
 
 prereq: incs srcs preludes
 
diff --git a/enc/make_encdb.rb b/enc/make_encdb.rb
index 013eabe1d7..6f71c3dfe6 100755
--- a/enc/make_encdb.rb
+++ b/enc/make_encdb.rb
@@ -65,12 +65,6 @@ end
 
 result = encodings.map {|e| %[ENC_DEFINE("#{e}");\n]}.join + lines.join + 
   "\n#define ENCODING_COUNT #{count}\n"
-mode = IO::RDWR|IO::CREAT
-mode |= IO::BINARY if defined?(IO::BINARY)
-open(outhdr, mode) do |f|
-  unless f.read == result
-    f.rewind
-    f.truncate(0)
-    f.print result
-  end
+open(outhdr, 'wb') do |f|
+  f.print result
 end
diff --git a/enc/trans/make_transdb.rb b/enc/trans/make_transdb.rb
index aae24fdbf4..762dc107e3 100644
--- a/enc/trans/make_transdb.rb
+++ b/enc/trans/make_transdb.rb
@@ -31,12 +31,6 @@ Dir.open(transdir) {|d| d.grep(/.+\.[ch]\z/)}.sort_by {|e|
   end
 end
 result = converters.map {|k, v| %[rb_declare_transcoder("%s", "%s", "%s");\n] % v}.join
-mode = IO::RDWR|IO::CREAT
-mode |= IO::BINARY if defined?(IO::BINARY)
-open(outhdr, mode) do |f|
-  unless f.read == result
-    f.rewind
-    f.truncate(0)
-    f.print result
-  end
+open(outhdr, 'wb') do |f|
+  f.print result
 end