diff --git a/ext/io/event/selector/epoll.c b/ext/io/event/selector/epoll.c
index 98d0490f..ca859130 100644
--- a/ext/io/event/selector/epoll.c
+++ b/ext/io/event/selector/epoll.c
@@ -473,6 +473,8 @@ VALUE process_wait_ensure(VALUE _arguments) {
 	return Qnil;
 }
 
+struct IO_Event_List_Type IO_Event_Selector_EPoll_process_wait_list_type = {};
+
 VALUE IO_Event_Selector_EPoll_process_wait(VALUE self, VALUE fiber, VALUE _pid, VALUE _flags) {
 	struct IO_Event_Selector_EPoll *selector = NULL;
 	TypedData_Get_Struct(self, struct IO_Event_Selector_EPoll, &IO_Event_Selector_EPoll_Type, selector);
@@ -489,7 +491,7 @@ VALUE IO_Event_Selector_EPoll_process_wait(VALUE self, VALUE fiber, VALUE _pid,
 	rb_update_max_fd(descriptor);
 	
 	struct IO_Event_Selector_EPoll_Waiting waiting = {
-		.list = {.type = 1},
+		.list = {.type = &IO_Event_Selector_EPoll_process_wait_list_type},
 		.fiber = fiber,
 		.events = IO_EVENT_READABLE,
 	};
@@ -538,6 +540,8 @@ VALUE io_wait_transfer(VALUE _arguments) {
 	}
 };
 
+struct IO_Event_List_Type IO_Event_Selector_EPoll_io_wait_list_type = {};
+
 VALUE IO_Event_Selector_EPoll_io_wait(VALUE self, VALUE fiber, VALUE io, VALUE events) {
 	struct IO_Event_Selector_EPoll *selector = NULL;
 	TypedData_Get_Struct(self, struct IO_Event_Selector_EPoll, &IO_Event_Selector_EPoll_Type, selector);
@@ -545,7 +549,7 @@ VALUE IO_Event_Selector_EPoll_io_wait(VALUE self, VALUE fiber, VALUE io, VALUE e
 	int descriptor = IO_Event_Selector_io_descriptor(io); 
 	
 	struct IO_Event_Selector_EPoll_Waiting waiting = {
-		.list = {.type = 1},
+		.list = {.type = &IO_Event_Selector_EPoll_io_wait_list_type},
 		.fiber = fiber,
 		.events = RB_NUM2INT(events),
 	};
diff --git a/ext/io/event/selector/kqueue.c b/ext/io/event/selector/kqueue.c
index 0515e1a8..432f305a 100644
--- a/ext/io/event/selector/kqueue.c
+++ b/ext/io/event/selector/kqueue.c
@@ -476,6 +476,8 @@ VALUE process_wait_ensure(VALUE _arguments) {
 	return Qnil;
 }
 
+struct IO_Event_List_Type IO_Event_Selector_KQueue_process_wait_list_type = {};
+
 VALUE IO_Event_Selector_KQueue_process_wait(VALUE self, VALUE fiber, VALUE _pid, VALUE _flags) {
 	struct IO_Event_Selector_KQueue *selector = NULL;
 	TypedData_Get_Struct(self, struct IO_Event_Selector_KQueue, &IO_Event_Selector_KQueue_Type, selector);
@@ -483,7 +485,7 @@ VALUE IO_Event_Selector_KQueue_process_wait(VALUE self, VALUE fiber, VALUE _pid,
 	pid_t pid = NUM2PIDT(_pid);
 	
 	struct IO_Event_Selector_KQueue_Waiting waiting = {
-		.list = {.type = 1},
+		.list = {.type = &IO_Event_Selector_KQueue_process_wait_list_type},
 		.fiber = fiber,
 		.events = IO_EVENT_EXIT,
 	};
@@ -536,6 +538,8 @@ VALUE io_wait_transfer(VALUE _arguments) {
 	}
 }
 
+struct IO_Event_List_Type IO_Event_Selector_KQueue_io_wait_list_type = {};
+
 VALUE IO_Event_Selector_KQueue_io_wait(VALUE self, VALUE fiber, VALUE io, VALUE events) {
 	struct IO_Event_Selector_KQueue *selector = NULL;
 	TypedData_Get_Struct(self, struct IO_Event_Selector_KQueue, &IO_Event_Selector_KQueue_Type, selector);
@@ -543,7 +547,7 @@ VALUE IO_Event_Selector_KQueue_io_wait(VALUE self, VALUE fiber, VALUE io, VALUE
 	int descriptor = IO_Event_Selector_io_descriptor(io);
 	
 	struct IO_Event_Selector_KQueue_Waiting waiting = {
-		.list = {.type = 1},
+		.list = {.type = &IO_Event_Selector_KQueue_io_wait_list_type},
 		.fiber = fiber,
 		.events = RB_NUM2INT(events),
 	};
diff --git a/ext/io/event/selector/list.h b/ext/io/event/selector/list.h
index a3fce77e..45bb5841 100644
--- a/ext/io/event/selector/list.h
+++ b/ext/io/event/selector/list.h
@@ -4,9 +4,12 @@
 #include <stdio.h>
 #include <assert.h>
 
+struct IO_Event_List_Type {
+};
+
 struct IO_Event_List {
 	struct IO_Event_List *head, *tail;
-	void *type;
+	struct IO_Event_List_Type *type;
 };
 
 inline static void IO_Event_List_initialize(struct IO_Event_List *list)