diff --git a/common.mk b/common.mk
index 5e34aedcbc..ad492c0079 100644
--- a/common.mk
+++ b/common.mk
@@ -1644,19 +1644,19 @@ $(UNICODE_HDR_DIR)/name2ctype.h:
 	$(MV) $@.new $@
 
 # the next non-comment line was:
-# $(UNICODE_HDR_DIR)/casefold.h: $(srcdir)/enc/unicode/case-folding.rb \
+# $(UNICODE_HDR_DIR)/casefold.h: $(tooldir)/enc-case-folding.rb \
 # but was changed to make sure CI works on systems that don't have gperf
 unicode-up: $(UNICODE_DATA_HEADERS)
 
 $(UNICODE_HDR_DIR)/$(ALWAYS_UPDATE_UNICODE:yes=casefold.h): \
-		$(srcdir)/enc/unicode/case-folding.rb \
+		$(tooldir)/enc-case-folding.rb \
 		$(UNICODE_SRC_DATA_DIR)/UnicodeData.txt \
 		$(UNICODE_SRC_DATA_DIR)/SpecialCasing.txt \
 		$(UNICODE_SRC_DATA_DIR)/CaseFolding.txt
 
 $(UNICODE_HDR_DIR)/casefold.h:
 	$(MAKEDIRS) $(@D)
-	$(Q) $(BASERUBY) $(srcdir)/enc/unicode/case-folding.rb \
+	$(Q) $(BASERUBY) $(tooldir)/enc-case-folding.rb \
 		--output-file=$@ \
 		--mapping-data-directory=$(UNICODE_SRC_DATA_DIR)
 
diff --git a/enc/unicode/case-folding.rb b/tool/enc-case-folding.rb
old mode 100644
new mode 100755
similarity index 98%
rename from enc/unicode/case-folding.rb
rename to tool/enc-case-folding.rb
index 4a29fdebf7..6d43a27df8
--- a/enc/unicode/case-folding.rb
+++ b/tool/enc-case-folding.rb
@@ -3,12 +3,12 @@ require 'stringio'
 
 # Usage (for case folding only):
 #   $ wget http://www.unicode.org/Public/UNIDATA/CaseFolding.txt
-#   $ ruby case-folding.rb CaseFolding.txt -o casefold.h
+#   $ ruby enc-case-folding.rb CaseFolding.txt -o casefold.h
 #  or (for case folding and case mapping):
 #   $ wget http://www.unicode.org/Public/UNIDATA/CaseFolding.txt
 #   $ wget http://www.unicode.org/Public/UNIDATA/UnicodeData.txt
 #   $ wget http://www.unicode.org/Public/UNIDATA/SpecialCasing.txt
-#   $ ruby case-folding.rb -m . -o casefold.h
+#   $ ruby enc-case-folding.rb -m . -o casefold.h
 # using -d or --debug will include UTF-8 characters in comments for debugging
 
 class CaseFolding
@@ -158,7 +158,7 @@ class CaseFolding
   def display(dest, mapping_data)
     # print the header
     dest.print("/* DO NOT EDIT THIS FILE. */\n")
-    dest.print("/* Generated by enc/unicode/case-folding.rb */\n\n")
+    dest.print("/* Generated by enc-case-folding.rb */\n\n")
 
     versions = version.scan(/\d+/)
     dest.print("#if defined ONIG_UNICODE_VERSION_STRING && !( \\\n")