diff --git a/uuid.erl b/uuid.erl
index 2986df0..8f75e9c 100644
--- a/uuid.erl
+++ b/uuid.erl
@@ -33,7 +33,10 @@
 
 % Generates a random binary UUID.
 v4() ->
-  v4(crypto:rand_uniform(1, round(math:pow(2, 48))) - 1, crypto:rand_uniform(1, round(math:pow(2, 12))) - 1, crypto:rand_uniform(1, round(math:pow(2, 32))) - 1, crypto:rand_uniform(1, round(math:pow(2, 30))) - 1).
+    v4(crypto:rand_uniform(1, 1 bsl 48),
+       crypto:rand_uniform(1, 1 bsl 12),
+       crypto:rand_uniform(1, 1 bsl 32),
+       crypto:rand_uniform(1, 1 bsl 30)).
 
 v4(R1, R2, R3, R4) ->
     <<R1:48, 4:4, R2:12, 2:2, R3:32, R4: 30>>.