diff --git a/CREDITS b/CREDITS
index e1d70c10..ffc667b0 100644
--- a/CREDITS
+++ b/CREDITS
@@ -48,3 +48,8 @@
   Email::         danielneis at gmail.com
   Contribution::  Patch to add Sprite#undraw (based on UpdateGroup#undraw).
   Date::          2007-07-29 (r460).
+
+- <b>ippa</a>
+  Email::         admin@rubylicio.us
+  Contribution::  Patch to optimize Rect#collide_rect?
+  Date::          2007-11-21 (595)
diff --git a/lib/rubygame/rect.rb b/lib/rubygame/rect.rb
index d4103d97..8651f5c0 100644
--- a/lib/rubygame/rect.rb
+++ b/lib/rubygame/rect.rb
@@ -498,10 +498,8 @@ def collide_point?(x,y)
 	def collide_rect?(rect)
 		nself = self.normalize
 		rect  = Rect.new_from_object(rect).normalize!
-		return ((( (rect.l)..(rect.r) ).include?(nself.l)  or\
-						 ((nself.l)..(nself.r)).include?( rect.l)) and\
-						(( (rect.t)..(rect.b) ).include?(nself.t)  or\
-						 ((nself.t)..(nself.b)).include?( rect.t)))
+		return ((nself.l >= rect.l && nself.l <= rect.r) or (rect.l >= nself.l && rect.l <= nself.r)) &&
+		       ((nself.t >= rect.t && nself.t <= rect.b) or (rect.t >= nself.t && rect.t <= nself.b))
 	end
 
 	# True if the given Rect is totally within the caller. Borders may