diff --git a/ChangeLog b/ChangeLog
index be6935c55c..c11810b0ee 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Sep 26 18:09:51 2000  WATANABE Hirofumi  <eban@ruby-lang.org>
+
+	* string.c: include <math.h>
+
 Tue Sep 26 15:59:50 2000  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* object.c (rb_mod_dup): metaclasses of class/module should not be
diff --git a/string.c b/string.c
index 5eb5d248ed..40207e5ba4 100644
--- a/string.c
+++ b/string.c
@@ -18,6 +18,7 @@
 #define BEG(no) regs->beg[no]
 #define END(no) regs->end[no]
 
+#include <math.h>
 #include <ctype.h>
 
 #ifdef HAVE_UNISTD_H