diff --git a/.gdbinit b/.gdbinit
index 9d3d455596..f54a38fb16 100644
--- a/.gdbinit
+++ b/.gdbinit
@@ -2,7 +2,7 @@ define rp
   if (VALUE)$arg0 & 1
     printf "FIXNUM: %d\n", $arg0 >> 1
   else
-  if ((VALUE)$arg0 & ~(~(VALUE)0<<RUBY_SPECIAL_SHIFT)) == SYMBOL_FLAG
+  if ((VALUE)$arg0 & ~(~(VALUE)0<<RUBY_SPECIAL_SHIFT)) == RUBY_SYMBOL_FLAG
     printf "SYMBOL(%d)\n", $arg0 >> 8
   else
   if $arg0 == 0
diff --git a/ChangeLog b/ChangeLog
index 018b7cfc3a..90741ec75f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -18,6 +18,14 @@ Fri Aug 17 01:21:29 2007  Koichi Sasada  <ko1@atdot.net>
 
 	* insns.def (throw): insert a RUBY_VM_CHECK_INTS(). [ruby-dev:31361]
 
+Thu Aug 16 20:40:50 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* bignum.c (bigtrunc): RBIGNUM(x)->len may be zero.  out of bound
+	  access.  [ruby-dev:31404]
+
+	* sprintf.c (rb_str_format): small float should not call
+	  rb_dbl2big(). 
+
 Thu Aug 16 22:10:06 2007  Koichi Sasada  <ko1@atdot.net>
 
 	* compile.c (iseq_compile_each): fix next/redo stack consistency.
diff --git a/bignum.c b/bignum.c
index fc7329b5e5..fcfe64983a 100644
--- a/bignum.c
+++ b/bignum.c
@@ -97,6 +97,7 @@ bigtrunc(VALUE x)
     long len = RBIGNUM(x)->len;
     BDIGIT *ds = BDIGITS(x);
 
+    if (len == 0) return x;
     while (--len && !ds[len]);
     RBIGNUM(x)->len = ++len;
     return x;
diff --git a/sprintf.c b/sprintf.c
index 78438bf55b..1c60837e78 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -522,6 +522,10 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 	      bin_retry:
 		switch (TYPE(val)) {
 		  case T_FLOAT:
+		    if (FIXABLE((long)RFLOAT(val)->value)) {
+			val = LONG2FIX((long)RFLOAT(val)->value);
+			goto bin_retry;
+		    }
 		    val = rb_dbl2big(RFLOAT(val)->value);
 		    if (FIXNUM_P(val)) goto bin_retry;
 		    bignum = 1;