diff --git a/ChangeLog b/ChangeLog
index 2ef63346a4..17c6fbe20b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun May  9 16:28:15 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* cont.c (fiber_initialize_machine_stack_context): try to release
+	  unnecessary fibers and retry to create.  based on a patch from
+	  masaya tarui at [ruby-dev:41230].
+
 Sun May  9 08:32:56 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/json/generator/generator.c (fbuffer_inc_capa):
diff --git a/cont.c b/cont.c
index 54f05aba8c..8bb9821c7c 100644
--- a/cont.c
+++ b/cont.c
@@ -548,6 +548,14 @@ fiber_initialize_machine_stack_context(rb_fiber_t *fib, size_t size)
 
 #ifdef _WIN32
     fib->fib_handle = CreateFiberEx(size - 1, size, 0, fiber_entry, NULL);
+    if (!fib->fib_handle) {
+	/* try to release unnecessary fibers & retry to create */
+	rb_gc();
+	fib->fib_handle = CreateFiberEx(size - 1, size, 0, fiber_entry, NULL);
+	if (!fib->fib_handle) {
+	    rb_raise(rb_eFiberError, "can't create fiber");
+	}
+    }
 #else /* not WIN32 */
     ucontext_t *context = &fib->context;
     VALUE *ptr;