diff --git a/ChangeLog b/ChangeLog
index c2b62fd5f7..1a7df151a5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,6 @@
-Sat Aug 14 15:11:01 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Sat Aug 14 15:17:36 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* regcomp.c (onig_memsize): constified.
 
 	* gc.h (rb_objspace_each_objects): used in objspace.
 
diff --git a/ext/objspace/objspace.c b/ext/objspace/objspace.c
index 32b5b1ee41..b557cc9ab3 100644
--- a/ext/objspace/objspace.c
+++ b/ext/objspace/objspace.c
@@ -29,11 +29,11 @@
 #include <ruby/re.h>
 #include <../../node.h>
 #include <../../gc.h>
+#include <../../regint.h>
 
 size_t rb_str_memsize(VALUE);
 size_t rb_ary_memsize(VALUE);
 size_t rb_io_memsize(rb_io_t *);
-size_t onig_memsize(regex_t *);
 size_t rb_generic_ivar_memsize(VALUE);
 size_t rb_objspace_data_type_memsize(VALUE obj);
 
diff --git a/regcomp.c b/regcomp.c
index b681e669bf..ef4c086242 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -5249,7 +5249,7 @@ onig_free(regex_t* reg)
 }
 
 size_t
-onig_memsize(regex_t *reg)
+onig_memsize(const regex_t *reg)
 {
     size_t size = sizeof(regex_t);
     if (IS_NOT_NULL(reg->p))                size += reg->alloc;
diff --git a/regint.h b/regint.h
index c0c0e99815..633cd885c6 100644
--- a/regint.h
+++ b/regint.h
@@ -842,6 +842,8 @@ typedef int (*ONIGENC_INIT_PROPERTY_LIST_FUNC_TYPE)(void);
 
 extern int onigenc_property_list_init P_((ONIGENC_INIT_PROPERTY_LIST_FUNC_TYPE));
 
+extern size_t onig_memsize P_((const regex_t *reg));
+
 #if defined __GNUC__ && __GNUC__ >= 4
 #pragma GCC visibility pop
 #endif