diff --git a/ruby/compat.h b/ruby/compat.h
index 98c88816..d7a2ca78 100644
--- a/ruby/compat.h
+++ b/ruby/compat.h
@@ -35,6 +35,23 @@ extern VALUE s_enc_utf8_value;
 #endif
 
 
+/* ruby 1.8 and Rubinius */
+#ifndef RBIGNUM_POSITIVE_P
+# ifdef RUBINIUS
+#  define RBIGNUM_POSITIVE_P(b) (rb_funcall(b, rb_intern(">="), 1, INT2FIX(0)) == Qtrue)
+# else
+#  define RBIGNUM_POSITIVE_P(b) (RBIGNUM(b)->sign)
+# endif
+#endif
+
+
+/* Rubinius */
+#ifdef RUBINIUS
+static inline void rb_gc_enable() { return; }
+static inline void rb_gc_disable() { return; }
+#endif
+
+
 /* ruby 1.8.5 */
 #ifndef RSTRING_PTR
 #define RSTRING_PTR(s) (RSTRING(s)->ptr)
diff --git a/ruby/extconf.rb b/ruby/extconf.rb
index eb6a389f..f1d44ec1 100644
--- a/ruby/extconf.rb
+++ b/ruby/extconf.rb
@@ -1,5 +1,5 @@
 require 'mkmf'
 require './version.rb'
-$CFLAGS << %[ -I.. -Wall -O4 -DMESSAGEPACK_VERSION=\\"#{MessagePack::VERSION}\\"]
+$CFLAGS << %[ -I.. -Wall -O4 -DMESSAGEPACK_VERSION=\\"#{MessagePack::VERSION}\\" -g]
 create_makefile('msgpack')
 
diff --git a/ruby/pack.c b/ruby/pack.c
index 49b69fc9..8ce46aaf 100644
--- a/ruby/pack.c
+++ b/ruby/pack.c
@@ -118,10 +118,6 @@ static VALUE MessagePack_Fixnum_to_msgpack(int argc, VALUE *argv, VALUE self)
 }
 
 
-#ifndef RBIGNUM_SIGN  // Ruby 1.8
-#define RBIGNUM_SIGN(b) (RBIGNUM(b)->sign)
-#endif
-
 /*
  * Document-method: Bignum#to_msgpack
  *
@@ -133,9 +129,9 @@ static VALUE MessagePack_Fixnum_to_msgpack(int argc, VALUE *argv, VALUE self)
 static VALUE MessagePack_Bignum_to_msgpack(int argc, VALUE *argv, VALUE self)
 {
 	ARG_BUFFER(out, argc, argv);
-	if(RBIGNUM_SIGN(self)) {  // positive
+	if(RBIGNUM_POSITIVE_P(self)) {
 		msgpack_pack_uint64(out, rb_big2ull(self));
-	} else {  // negative
+	} else {
 		msgpack_pack_int64(out, rb_big2ll(self));
 	}
 	return out;