diff --git a/ChangeLog b/ChangeLog
index 532945f089..b5dc9e208d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Aug  4 13:49:36 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* bignum.c (rb_big2str0, bigsqr): made interruptible.  [ruby-Bugs-20622]
+
 Mon Aug  4 13:39:53 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/openssl/openssl_missing.h (d2i_of_void): define for older
diff --git a/bignum.c b/bignum.c
index e3d531ceaf..c23b76b1fe 100644
--- a/bignum.c
+++ b/bignum.c
@@ -11,6 +11,7 @@
 **********************************************************************/
 
 #include "ruby.h"
+#include "rubysig.h"
 
 #include <math.h>
 #include <ctype.h>
@@ -709,6 +710,7 @@ rb_big2str0(x, base, trim)
     s = RSTRING(ss)->ptr;
 
     s[0] = RBIGNUM(x)->sign ? '+' : '-';
+    TRAP_BEG;
     while (i && j > 1) {
 	long k = i;
 	BDIGIT_DBL num = 0;
@@ -738,6 +740,7 @@ rb_big2str0(x, base, trim)
 	RSTRING(ss)->len = i;
     }
     s[RSTRING(ss)->len] = '\0';
+    TRAP_END;
 
     return ss;
 }
diff --git a/common.mk b/common.mk
index f751fecfb5..6d5b35dee6 100644
--- a/common.mk
+++ b/common.mk
@@ -341,7 +341,8 @@ array.$(OBJEXT): {$(VPATH)}array.c {$(VPATH)}ruby.h config.h \
   {$(VPATH)}defines.h {$(VPATH)}intern.h {$(VPATH)}missing.h \
   {$(VPATH)}util.h {$(VPATH)}st.h
 bignum.$(OBJEXT): {$(VPATH)}bignum.c {$(VPATH)}ruby.h config.h \
-  {$(VPATH)}defines.h {$(VPATH)}intern.h {$(VPATH)}missing.h
+  {$(VPATH)}defines.h {$(VPATH)}intern.h {$(VPATH)}missing.h \
+  {$(VPATH)}rubysig.h
 class.$(OBJEXT): {$(VPATH)}class.c {$(VPATH)}ruby.h config.h \
   {$(VPATH)}defines.h {$(VPATH)}intern.h {$(VPATH)}missing.h \
   {$(VPATH)}rubysig.h {$(VPATH)}node.h {$(VPATH)}st.h
diff --git a/version.h b/version.h
index 2f4ea645d4..b5c3c1cafe 100644
--- a/version.h
+++ b/version.h
@@ -2,7 +2,7 @@
 #define RUBY_RELEASE_DATE "2008-08-04"
 #define RUBY_VERSION_CODE 186
 #define RUBY_RELEASE_CODE 20080804
-#define RUBY_PATCHLEVEL 282
+#define RUBY_PATCHLEVEL 283
 
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 8