diff --git a/ChangeLog b/ChangeLog
index aa58782dc2..a44c523dcd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,13 @@
+Thu Feb 19 02:42:19 2004  Minero Aoki  <aamine@loveruby.net>
+
+	* ext/strscan/strscan.c: don't use rb_eval_string, it defines
+	  classes under the module when required in module clauses.
+	  [ruby-dev:22951]
+
 Thu Feb 19 02:37:28 2004  Minero Aoki  <aamine@loveruby.net>
 
-	* ext/strscan/strscan.c: merge documentation from 1.8 branch. Thanks Gavin Sinclair.
+	* ext/strscan/strscan.c: merge documentation from 1.8 branch.
+	  Thanks Gavin Sinclair.
 
 Wed Feb 19 00:20:00 2004  Gavin Sinclair <gsinclair@soyabean.com.au>
 
diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index 39d3d8bcb6..8997cbf8b4 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -1245,10 +1245,14 @@ inspect2(p)
 void
 Init_strscan()
 {
-    volatile VALUE tmp;
+    ID id_scanerr = rb_intern("ScanError");
+    VALUE tmp;
 
     StringScanner = rb_define_class("StringScanner", rb_cObject);
-    ScanError = rb_eval_string("class StringScanner; class Error < StandardError; end; end; ScanError = StringScanner::Error unless defined?(ScanError); StringScanner::Error");
+    ScanError = rb_define_class_under(StringScanner, "Error", rb_eStandardError);
+    if (!rb_const_defined(rb_cObject, id_scanerr)) {
+	rb_const_set(rb_cObject, id_scanerr, ScanError);
+    }
     tmp = rb_str_new2(STRSCAN_VERSION);
     rb_obj_freeze(tmp);
     rb_const_set(StringScanner, rb_intern("Version"), tmp);