diff --git a/ChangeLog b/ChangeLog
index 49193ba133..43b6623f1f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri May 11 15:09:52 2001  WATANABE Hirofumi  <eban@ruby-lang.org>
+
+	* ruby.h (rb_string_value): add volatile to avoid compiler warning.
+
+	* string.c (rb_string_value): ditto.
+
 Fri May 11 02:00:44 2001  Ryo HAYASAKA  <ryoh@jaist.ac.jp>
 
 	* bignum.c (bigdivrem): access boundary bug.
diff --git a/ruby.h b/ruby.h
index 971a7e06b9..81a87b02be 100644
--- a/ruby.h
+++ b/ruby.h
@@ -186,7 +186,7 @@ void rb_check_type _((VALUE,int));
 #define Check_Type(v,t) rb_check_type((VALUE)(v),t)
 
 VALUE rb_str_to_str _((VALUE));
-VALUE rb_string_value _((VALUE*));
+VALUE rb_string_value _((volatile VALUE*));
 
 #define StringValue(v) if (TYPE(v) != T_STRING) rb_string_value(&(v))
 void rb_check_safe_str _((VALUE));
diff --git a/string.c b/string.c
index b760301137..0706318361 100644
--- a/string.c
+++ b/string.c
@@ -141,7 +141,7 @@ rb_str_to_str(str)
 
 VALUE
 rb_string_value(ptr)
-    VALUE *ptr;
+    volatile VALUE *ptr;
 {
     return *ptr = rb_str_to_str(*ptr);
 }