diff --git a/ChangeLog b/ChangeLog
index 8708125e9e..3524a204e3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Mon Dec 17 18:42:23 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* string.c (scan_once): need no encoding compatibility check.
+	  it's done inside of re_reg_seach().
+
+	* string.c (rb_str_split_m): ditto.
+
+	* re.c (rb_reg_regsub): ditto.
+
 Mon Dec 17 17:50:30 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* string.c (rb_str_index): check if substring is broken.
diff --git a/re.c b/re.c
index 4559d02be5..ce1d66863a 100644
--- a/re.c
+++ b/re.c
@@ -2695,7 +2695,6 @@ rb_reg_regsub(VALUE str, VALUE src, struct re_registers *regs, VALUE regexp)
     int no, clen;
     rb_encoding *enc = rb_enc_check(str, src);
 
-    rb_enc_check(str, regexp);
     p = s = RSTRING_PTR(str);
     e = s + RSTRING_LEN(str);
 
diff --git a/string.c b/string.c
index 76a0049530..62f5c31380 100644
--- a/string.c
+++ b/string.c
@@ -4129,9 +4129,6 @@ rb_str_split_m(int argc, VALUE *argv, VALUE str)
 	int last_null = 0;
 	struct re_registers *regs;
 
-	if (RREGEXP(spat)->len != 0) {
-	    enc = rb_enc_check(str, spat);
-	}
 	while ((end = rb_reg_search(spat, str, start, 0)) >= 0) {
 	    regs = RMATCH(rb_backref_get())->regs;
 	    if (start == end && BEG(0) == END(0)) {
@@ -4733,7 +4730,7 @@ scan_once(VALUE str, VALUE pat, long *start)
     struct re_registers *regs;
     long i;
 
-    enc = rb_enc_check(str, pat);
+    enc = rb_enc_get(str);
     if (rb_reg_search(pat, str, *start, 0) >= 0) {
 	match = rb_backref_get();
 	regs = RMATCH(match)->regs;