diff --git a/Cargo.toml b/Cargo.toml
index 6778a5a..3161016 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,5 +9,5 @@ categories = ["algorithms"]
 keywords = ["glicko", "elo", "rating", "skill"]
 
 [dev-dependencies]
-approx = "0.4"
+approx = "0.5"