diff --git a/ChangeLog b/ChangeLog
index 75a6b25963..90f81752a6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Sep 28 12:04:18 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* string.c (str_new): sets empty string to coderange 7bit.
+	  [ruby-core:18993]
+
 Sun Sep 28 09:39:48 2008  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* lib/mathn.rb ({Fixnum,Bignum,Float}#**): may produce complex
diff --git a/string.c b/string.c
index 990694f24f..7d6f30555a 100644
--- a/string.c
+++ b/string.c
@@ -395,6 +395,9 @@ str_new(VALUE klass, const char *ptr, long len)
 	RSTRING(str)->as.heap.ptr = ALLOC_N(char,len+1);
 	STR_SET_NOEMBED(str);
     }
+    else if (len == 0) {
+	ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
+    }
     if (ptr) {
 	memcpy(RSTRING_PTR(str), ptr, len);
     }