diff --git a/ChangeLog b/ChangeLog
index 61f18ac794..aa28caad23 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Apr 26 22:36:11 2001  WATANABE Hirofumi  <eban@ruby-lang.org>
+
+	* configure.in:  don't use tzname on cygwin 1.3.1+.
+
+	* configure.in: add -mieee/-ieee to CFLAGS on OSF1/Alpha
+	  to disable "DIVISION BY ZERO" exception.
+
 Tue Apr 24 16:03:25 2001  Hiroshi Igarashi  <iga@ruby-lang.org>
 
 	* ext/extmk.rb.in: add target `distclean' in Makefile for extlib.
diff --git a/configure.in b/configure.in
index 6910091f92..2e043a497e 100644
--- a/configure.in
+++ b/configure.in
@@ -185,7 +185,8 @@ rhapsody*)	;;
 darwin*)	LIBS="-lobjc $LIBS";;
 human*)		ac_cv_func_getpgrp_void=yes;;
 beos*)		;;
-cygwin*)	rb_cv_have_daylight=no;;
+cygwin*)	rb_cv_have_daylight=no
+		ac_cv_var_tzname=no;;
 mingw*)		LIBS="-lwsock32 -lmsvcrt $LIBS"
 		ac_cv_header_a_out_h=no
 		ac_cv_header_pwd_h=no
@@ -241,6 +242,13 @@ linux*)		LIBS="-lm $LIBS"
 		alpha*)
 		    CFLAGS="-mieee $CFLAGS" ;;
 		esac ;;
+osf*)		LIBS="-lm $LIBS"
+		case "$target_cpu"::"$without_gcc" in
+		alpha*::no)
+		    CFLAGS="-mieee $CFLAGS" ;;
+		alpha*::yes)
+		    CFLAGS="-ieee $CFLAGS" ;;
+		esac ;;
 *) LIBS="-lm $LIBS";;
 esac
 AC_CHECK_LIB(crypt, crypt)