diff --git a/file.h b/file.h
index 95ecefe..eb0688c 100644
--- a/file.h
+++ b/file.h
@@ -97,7 +97,7 @@
 	/*
 	 * For use by the io engine
 	 */
-	uintptr_t engine_data;
+	uint64_t engine_data;
 
 	/*
 	 * if io is protected by a semaphore, this is set