Index: Languages/Ruby/ironruby/Builtins/MatchData.cs
===================================================================
--- Languages/Ruby/ironruby/Builtins/MatchData.cs	(revision 22765)
+++ Languages/Ruby/ironruby/Builtins/MatchData.cs	(working copy)
@@ -69,7 +69,7 @@
 
         public MutableString GetGroupValue(RubyContext/*!*/ context, int index) {
             var group = Groups[index];
-            return group.Success ? MutableString.Create(group.Value).TaintBy(this, context) : null;
+            return group.Success ? MutableString.Create(group.Value, context.KCode ?? RubyEncoding.Default).TaintBy(this, context) : null;
         }
 
         public Group/*!*/ GetExistingGroup(int index) {
Index: Languages/Ruby/ironruby/Runtime/RubyScope.cs
===================================================================
--- Languages/Ruby/ironruby/Runtime/RubyScope.cs	(revision 22765)
+++ Languages/Ruby/ironruby/Runtime/RubyScope.cs	(working copy)
@@ -509,7 +509,7 @@
             // we don't need to check index range, Groups indexer returns an unsuccessful group if out of range:
             Group group;
             if (_currentMatch != null && (group = _currentMatch.Groups[index]).Success) {
-                return MutableString.Create(group.Value).TaintBy(_currentMatch.OriginalString);
+                return MutableString.Create(group.Value, RubyContext.KCode ?? RubyEncoding.Default).TaintBy(_currentMatch.OriginalString);
             }
 
             return null;
@@ -521,7 +521,7 @@
                 for (int i = _currentMatch.Groups.Count - 1; i >= 0; i--) {
                     Group group = _currentMatch.Groups[i];
                     if (group.Success) {
-                        return MutableString.Create(group.Value).TaintBy(_currentMatch.OriginalString);
+                        return MutableString.Create(group.Value, RubyContext.KCode ?? RubyEncoding.Default).TaintBy(_currentMatch.OriginalString);
                     }
                 }
             }