diff --git a/src/test/run-pass/over-constrained-vregs.rs b/src/test/run-pass/over-constrained-vregs.rs
index 1118638fe0713..c2b42ac1c8163 100644
--- a/src/test/run-pass/over-constrained-vregs.rs
+++ b/src/test/run-pass/over-constrained-vregs.rs
@@ -11,7 +11,7 @@
 // Regression test for issue #152.
 pub fn main() {
     let mut b: uint = 1_usize;
-    while b <= 32_usize {
+    while b < std::mem::size_of::<usize>() {
         0_usize << b;
         b <<= 1_usize;
         println!("{}", b);