diff --git a/Cargo.toml b/Cargo.toml
index 89ef53a9..11204f7a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -39,7 +39,7 @@ serde = { version = "1.0", features = ["derive"], optional = true }
 json = { version = "0.12", optional = true }
 arrow2 = { version = "0.18", features = ["io_parquet", "io_parquet_compression"], optional = true }
 num-complex = { version = "0.4", optional = true }
-lambert_w = { version = "0.3.0", default-features = false, features = ["24bits", "50bits"] }
+lambert_w = { version = "0.4.0", default-features = false, features = ["24bits", "50bits"] }
 
 [package.metadata.docs.rs]
 rustdoc-args = [ "--html-in-header", "katex-header.html", "--cfg", "docsrs"]
diff --git a/src/special/function.rs b/src/special/function.rs
index e81c86ac..ec33844f 100644
--- a/src/special/function.rs
+++ b/src/special/function.rs
@@ -135,7 +135,6 @@ pub fn lambert_w0(z: f64, mode: LambertWAccuracyMode) -> f64 {
         LambertWAccuracyMode::Precise => lambert_w::lambert_w_0(z),
         LambertWAccuracyMode::Simple => lambert_w::sp_lambert_w_0(z),
     }
-    .unwrap_or(f64::NAN)
 }
 
 /// The secondary branch of the Lambert W function, W_-1(`z`).
@@ -155,7 +154,6 @@ pub fn lambert_wm1(z: f64, mode: LambertWAccuracyMode) -> f64 {
         LambertWAccuracyMode::Precise => lambert_w::lambert_w_m1(z),
         LambertWAccuracyMode::Simple => lambert_w::sp_lambert_w_m1(z),
     }
-    .unwrap_or(f64::NAN)
 }
 
 /// Decides the accuracy mode of the Lambert W functions.