diff --git a/src/libnum/bigint.rs b/src/libnum/bigint.rs
index 345dce12feda7..661b5fa6f438b 100644
--- a/src/libnum/bigint.rs
+++ b/src/libnum/bigint.rs
@@ -1261,7 +1261,7 @@ impl FromStrRadix for BigInt {
     }
 }
 
-trait RandBigInt {
+pub trait RandBigInt {
     /// Generate a random `BigUint` of the given bit size.
     fn gen_biguint(&mut self, bit_size: uint) -> BigUint;