1 files changed, 12 insertions, 2 deletions
diff --git a/lib/webrick/httputils.rb b/lib/webrick/httputils.rb
index a0ca3a48c7..a5f0632b86 100644
--- a/lib/webrick/httputils.rb
+++ b/lib/webrick/httputils.rb
@@ -437,8 +437,18 @@ module WEBrick
 
     def _make_regex(str) /([#{Regexp.escape(str)}])/n end
     def _make_regex!(str) /([^#{Regexp.escape(str)}])/n end
-    def _escape(str, regex) str.gsub(regex){ "%%%02X" % $1.ord } end
-    def _unescape(str, regex) str.gsub(regex){ $1.hex.chr } end
+    def _escape(str, regex)
+      str = str.b
+      str.gsub!(regex) {"%%%02X" % $1.ord}
+      # %-escaped string should contain US-ASCII only
+      str.force_encoding(Encoding::US_ASCII)
+    end
+    def _unescape(str, regex)
+      str = str.b
+      str.gsub!(regex) {$1.hex.chr}
+      # encoding of %-unescaped string is unknown
+      str
+    end
 
     UNESCAPED = _make_regex(control+space+delims+unwise+nonascii)
     UNESCAPED_FORM = _make_regex(reserved+control+delims+unwise+nonascii)