diff --git a/README.md b/README.md
index f665269..3b379e5 100644
--- a/README.md
+++ b/README.md
@@ -78,8 +78,8 @@ use lambert_w::{lambert_w0, lambert_wm1};
 let big = lambert_w0(f64::MAX);
 let tiny = lambert_wm1(-1e-308);
 
-assert_relative_eq!(big, 703.2270331047702, max_relative = 1e-15);
-assert_relative_eq!(tiny, -715.7695669234213, max_relative = 1e-15);
+assert_relative_eq!(big, 703.2270331047702, max_relative = 4e-16);
+assert_relative_eq!(tiny, -715.7695669234213, max_relative = 4e-16);
 ```
 
 ## License
diff --git a/src/lib.rs b/src/lib.rs
index 988d940..fa7a014 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -83,8 +83,8 @@ use lambert_w::{lambert_w0, lambert_wm1};
 let big = lambert_w0(f64::MAX);
 let tiny = lambert_wm1(-1e-308);
 
-assert_relative_eq!(big, 703.2270331047702, max_relative = 1e-15);
-assert_relative_eq!(tiny, -715.7695669234213, max_relative = 1e-15);
+assert_relative_eq!(big, 703.2270331047702, max_relative = 4e-16);
+assert_relative_eq!(tiny, -715.7695669234213, max_relative = 4e-16);
 ```
 "#
 )]