diff --git a/Cargo.toml b/Cargo.toml
index e69fb7a..05b570b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -57,7 +57,7 @@ jsonwebtoken = "5.0.1"
 u2f = "0.1.2"
 
 # Yubico Library
-yubico = { version = "=0.4.0", default-features = false }
+yubico = { version = "=0.4.0", features = ["online"], default-features = false }
 
 # A `dotenv` implementation for Rust
 dotenv = { version = "0.13.0", default-features = false }