diff --git a/tail/tail.rs b/tail/tail.rs
index 50588d8a5..5ae4ca614 100644
--- a/tail/tail.rs
+++ b/tail/tail.rs
@@ -29,7 +29,7 @@ fn main () { uumain(os::args()); }
 
 pub fn uumain(args: Vec<String>) {
     let mut line_count = 10u;
-    let mut sleep_sec = 1000u;
+    let mut sleep_sec = 1000u64;
 
     // handle obsolete -number syntax
     let options = match obsolete(args.tail()) {