diff --git a/lib/paseto/paserk_types.rb b/lib/paseto/paserk_types.rb
index c7555be..7572088 100644
--- a/lib/paseto/paserk_types.rb
+++ b/lib/paseto/paserk_types.rb
@@ -25,17 +25,16 @@ class PaserkTypes < T::Enum
 
     sig { params(input: String).returns(Interface::Key) }
     def generate(input) # rubocop:disable Metrics/MethodLength, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
-      input_size = input.bytesize
       case self
-      in K3LocalWrap | K3LocalPBKW | K3Local if input_size == V3::Local::KEY_SIZE
+      in K3LocalWrap | K3LocalPBKW | K3Local if input.size == V3::Local::KEY_SIZE
         V3::Local.new(ikm: input)
-      in K3SecretWrap | K3SecretPBKW | K3Secret if input_size == V4::Public::KEY_SIZE
+      in K3SecretWrap | K3SecretPBKW | K3Secret if input.size == V4::Public::KEY_SIZE
         V3::Public.from_scalar_bytes(input)
       in K3Public
         V3::Public.from_public_bytes(input)
-      in K4LocalWrap | K4LocalPBKW | K4Local if Paseto::HAS_RBNACL && input_size == V4::Local::KEY_SIZE
+      in K4LocalWrap | K4LocalPBKW | K4Local if Paseto::HAS_RBNACL && input.size == V4::Local::KEY_SIZE
         V4::Local.new(ikm: input)
-      in K4SecretWrap | K4SecretPBKW | K4Secret if Paseto::HAS_RBNACL && input_size == V4::Public::KEY_SIZE
+      in K4SecretWrap | K4SecretPBKW | K4Secret if Paseto::HAS_RBNACL && input.size == V4::Public::KEY_SIZE
         V4::Public.from_keypair(input)
       in K4Public
         V4::Public.from_public_bytes(input)