diff --git a/lib/fog/providers/aws.rb b/lib/fog/providers/aws.rb
index 9138da2eb..7ef39795c 100644
--- a/lib/fog/providers/aws.rb
+++ b/lib/fog/providers/aws.rb
@@ -46,7 +46,9 @@ module Fog
     end
 
     def self.escape(string)
-      string.gsub( /([^-a-zA-Z0-9_.~]+)/n ) { |match| '%' + match.unpack( 'H2' * match.size ).join( '%' ).upcase }
+      string.gsub(/([^a-zA-Z0-9_.\-~]+)/) {
+        "%" + $1.unpack("H2" * $1.bytesize).join("%").upcase
+      }
     end
 
     def self.signed_params(params, options = {})
diff --git a/tests/aws/signed_params_tests.rb b/tests/aws/signed_params_tests.rb
index 24ffec3d0..1df3950de 100644
--- a/tests/aws/signed_params_tests.rb
+++ b/tests/aws/signed_params_tests.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 Shindo.tests('AWS | signed_params', ['aws']) do
-  returns( Fog::AWS.escape( "'Stop!' said Fred_-~." ) ) { "%27Stop%21%27%20said%20Fred_-~." }
+  returns( Fog::AWS.escape( "'Stöp!' said Fred_-~." ) ) { "%27St%C3%B6p%21%27%20said%20Fred_-~." }
 end