diff --git a/bignum.c b/bignum.c
index 788eb4bfd2..25ca9be87e 100644
--- a/bignum.c
+++ b/bignum.c
@@ -706,7 +706,7 @@ rb_big2str0(x, base, trim)
 	while (k--) {
 	    s[--j] = ruby_digitmap[num % base];
 	    num /= base;
-	    if (!trim && j < 1) break;
+	    if (!trim && j <= 1) break;
 	    if (trim && i == 0 && num == 0) break;
 	}
     }
diff --git a/sprintf.c b/sprintf.c
index de997098ba..e32c456b63 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -18,6 +18,8 @@
 #include <math.h>
 
 #define BIT_DIGITS(N)   (((N)*146)/485 + 1)  /* log2(10) =~ 146/485 */
+#define BITSPERDIG (SIZEOF_BDIGITS*CHAR_BIT)
+#define EXTENDSIGN(n, l) (((~0 << (n)) >> (((n)*(l)) % BITSPERDIG)) & ~(~0 << (n)))
 
 static void fmt_setup _((char*,int,int,int,int));
 
@@ -36,7 +38,7 @@ remove_sign_bits(str, base)
 	}
     }
     else if (base == 8) {
-	if (*t == '3') t++;
+	*t |= EXTENDSIGN(3, strlen(t));
 	while (*t == '7') {
 	    t++;
 	}
diff --git a/version.h b/version.h
index e06387f288..381a571ce5 100644
--- a/version.h
+++ b/version.h
@@ -2,7 +2,7 @@
 #define RUBY_RELEASE_DATE "2008-06-08"
 #define RUBY_VERSION_CODE 186
 #define RUBY_RELEASE_CODE 20080608
-#define RUBY_PATCHLEVEL 150
+#define RUBY_PATCHLEVEL 151
 
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 8