diff --git a/ChangeLog b/ChangeLog
index 8051b8266e..fa5273c028 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Feb 15 18:23:54 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* string.c (rb_str_sub_bang, str_gsub): allows hash for replacement.
+
 Fri Feb 15 17:12:41 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* string.c (str_strlen): use search_nonascii() for performance.
diff --git a/string.c b/string.c
index f0ac3844e3..1d94ca29f7 100644
--- a/string.c
+++ b/string.c
@@ -2783,7 +2783,7 @@ get_pat(VALUE pat, int quote)
 static VALUE
 rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
 {
-    VALUE pat, repl, match;
+    VALUE pat, repl, match, hash = Qnil;
     struct re_registers *regs;
     int iter = 0;
     int tainted = 0;
@@ -2794,7 +2794,10 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
     }
     else if (argc == 2) {
 	repl = argv[1];
-	StringValue(repl);
+	hash = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
+	if (NIL_P(hash)) {
+	    StringValue(repl);
+	}
 	if (OBJ_TAINTED(repl)) tainted = 1;
     }
     else {
@@ -2818,6 +2821,9 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
 	    str_frozen_check(str);
 	    rb_backref_set(match);
 	}
+	else if (!NIL_P(hash)) {
+	    repl = rb_hash_aref(hash, rb_str_subseq(str, BEG(0), END(0) - BEG(0)));
+	}
 	else {
 	    repl = rb_reg_regsub(repl, str, regs, pat);
 	}
@@ -2904,7 +2910,7 @@ rb_str_sub(int argc, VALUE *argv, VALUE str)
 static VALUE
 str_gsub(int argc, VALUE *argv, VALUE str, int bang)
 {
-    VALUE pat, val, repl, match, dest;
+    VALUE pat, val, repl, match, dest, hash = Qnil;
     struct re_registers *regs;
     long beg, n;
     long offset, blen, slen, len;
@@ -2920,7 +2926,10 @@ str_gsub(int argc, VALUE *argv, VALUE str, int bang)
 	break;
       case 2:
 	repl = argv[1];
-	StringValue(repl);
+	hash = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
+	if (NIL_P(hash)) {
+	    StringValue(repl);
+	}
 	if (OBJ_TAINTED(repl)) tainted = 1;
 	break;
       default:
@@ -2956,6 +2965,9 @@ str_gsub(int argc, VALUE *argv, VALUE str, int bang)
 	    }
 	    rb_backref_set(match);
 	}
+	else if (!NIL_P(hash)) {
+	    val = rb_hash_aref(hash, rb_str_subseq(str, BEG(0), END(0) - BEG(0)));
+	}
 	else {
 	    val = rb_reg_regsub(repl, str, regs, pat);
 	}