diff --git a/ChangeLog b/ChangeLog
index 2cda9d637c..634c33566e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Aug 27 18:44:06 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* internal.h (rb_strftime_timespec): move to time.c because it depends
+	  encoding.h.
+
 Sat Aug 27 18:17:58 2011  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* strftime.c (rb_strftime_with_timespec): get enc argument to specify
diff --git a/internal.h b/internal.h
index 6e5773548e..3bd4d6a639 100644
--- a/internal.h
+++ b/internal.h
@@ -29,8 +29,6 @@ struct rb_classext_struct {
     struct st_table *const_tbl;
 };
 
-typedef struct OnigEncodingTypeST rb_encoding;
-
 #undef RCLASS_SUPER
 #define RCLASS_EXT(c) (RCLASS(c)->ptr)
 #define RCLASS_SUPER(c) (RCLASS_EXT(c)->super)
@@ -159,9 +157,6 @@ VALUE rb_reg_check_preprocess(VALUE);
 /* signal.c */
 int rb_get_next_signal(void);
 
-/* strftime.c */
-size_t rb_strftime_timespec(char *s, size_t maxsize, const char *format, rb_encoding *enc, const struct vtm *vtm, struct timespec *ts, int gmt);
-
 /* string.c */
 int rb_str_buf_cat_escaped_char(VALUE result, unsigned int c, int unicode_p);
 
diff --git a/time.c b/time.c
index 04ba4c54ed..c47b3569a0 100644
--- a/time.c
+++ b/time.c
@@ -16,6 +16,9 @@
 #include "ruby/encoding.h"
 #include "internal.h"
 
+/* strftime.c */
+size_t rb_strftime_timespec(char *s, size_t maxsize, const char *format, rb_encoding *enc, const struct vtm *vtm, struct timespec *ts, int gmt);
+
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif