diff --git a/src/cox.cr b/src/cox.cr
index 330844f..b656f22 100644
--- a/src/cox.cr
+++ b/src/cox.cr
@@ -16,7 +16,7 @@ module Cox
   def self.encrypt(data, nonce : Nonce, recipient_public_key : PublicKey, sender_secret_key : SecretKey)
     data_buffer = data.to_slice
     data_size = data_buffer.bytesize
-    output_buffer = Bytes.new(data_buffer.bytesize + LibSodium::MAC_BYTES)
+    output_buffer = Bytes.new(data_buffer.bytesize + LibSodium::MAC_SIZE)
     if LibSodium.crypto_box_easy(output_buffer.to_unsafe, data_buffer, data_size, nonce.pointer, recipient_public_key.pointer, sender_secret_key.pointer) != 0
       raise Error.new("crypto_box_easy")
     end
@@ -31,7 +31,7 @@ module Cox
   def self.decrypt(data, nonce : Nonce, sender_public_key : PublicKey, recipient_secret_key : SecretKey)
     data_buffer = data.to_slice
     data_size = data_buffer.bytesize
-    output_buffer = Bytes.new(data_buffer.bytesize - LibSodium::MAC_BYTES)
+    output_buffer = Bytes.new(data_buffer.bytesize - LibSodium::MAC_SIZE)
     if LibSodium.crypto_box_open_easy(output_buffer.to_unsafe, data_buffer.to_unsafe, data_size, nonce.pointer, sender_public_key.pointer, recipient_secret_key.pointer) != 0
       raise DecryptionFailed.new("crypto_box_open_easy")
     end
@@ -41,7 +41,7 @@ module Cox
   def self.sign_detached(message, secret_key : SignSecretKey)
     message_buffer = message.to_slice
     message_buffer_size = message_buffer.bytesize
-    signature_output_buffer = Bytes.new(LibSodium::SIGNATURE_BYTES)
+    signature_output_buffer = Bytes.new(LibSodium::SIGNATURE_SIZE)
 
     if LibSodium.crypto_sign_detached(signature_output_buffer.to_unsafe, 0, message_buffer.to_unsafe, message_buffer_size, secret_key.pointer) != 0
       raise Error.new("crypto_sign_detached")
diff --git a/src/cox/kdf.cr b/src/cox/kdf.cr
index 60fd277..5d333b7 100644
--- a/src/cox/kdf.cr
+++ b/src/cox/kdf.cr
@@ -3,22 +3,22 @@ module Cox
     property bytes : Bytes
 
     def initialize(bytes : Bytes)
-      if bytes.bytesize != LibSodium::KDF_KEY_BYTES
-        raise ArgumentError.new("bytes must be #{LibSodium::KDF_KEY_BYTES}, got #{bytes.bytesize}")
+      if bytes.bytesize != LibSodium::KDF_KEY_SIZE
+        raise ArgumentError.new("bytes must be #{LibSodium::KDF_KEY_SIZE}, got #{bytes.bytesize}")
       end
 
       @bytes = bytes
     end
 
     def initialize
-      @bytes = Random::Secure.random_bytes(LibSodium::KDF_KEY_BYTES)
+      @bytes = Random::Secure.random_bytes(LibSodium::KDF_KEY_SIZE)
     end
 
     # context must be 8 bytes
     # subkey_size must be 16..64 bytes as of libsodium 1.0.17
     def derive(context, subkey_size, subkey_id = 0)
-      if context.bytesize != LibSodium::KDF_CONTEXT_BYTES
-        raise ArgumentError.new("context must be #{LibSodium::KDF_CONTEXT_BYTES}, got #{context.bytesize}")
+      if context.bytesize != LibSodium::KDF_CONTEXT_SIZE
+        raise ArgumentError.new("context must be #{LibSodium::KDF_CONTEXT_SIZE}, got #{context.bytesize}")
       end
 
       subkey = Bytes.new subkey_size
diff --git a/src/cox/key_pair.cr b/src/cox/key_pair.cr
index e0c55dd..3bea256 100644
--- a/src/cox/key_pair.cr
+++ b/src/cox/key_pair.cr
@@ -13,8 +13,8 @@ module Cox
     end
 
     def self.new
-      public_key = Bytes.new(PublicKey::KEY_LENGTH)
-      secret_key = Bytes.new(SecretKey::KEY_LENGTH)
+      public_key = Bytes.new(PublicKey::KEY_SIZE)
+      secret_key = Bytes.new(SecretKey::KEY_SIZE)
 
       LibSodium.crypto_box_keypair(public_key.to_unsafe, secret_key.to_unsafe)
 
diff --git a/src/cox/lib_sodium.cr b/src/cox/lib_sodium.cr
index 9303fbe..11d7312 100644
--- a/src/cox/lib_sodium.cr
+++ b/src/cox/lib_sodium.cr
@@ -31,16 +31,16 @@ module Cox
     fun crypto_generichash_blake2b_saltbytes : LibC::SizeT
     fun crypto_generichash_blake2b_personalbytes : LibC::SizeT
 
-    PUBLIC_KEY_BYTES  = crypto_box_publickeybytes()
-    SECRET_KEY_BYTES  = crypto_box_secretkeybytes()
-    NONCE_BYTES       = crypto_box_noncebytes()
-    MAC_BYTES         = crypto_box_macbytes()
-    PUBLIC_SIGN_BYTES = crypto_sign_publickeybytes()
-    SECRET_SIGN_BYTES = crypto_sign_secretkeybytes()
-    SIGNATURE_BYTES   = crypto_sign_bytes()
-    KDF_KEY_BYTES     = crypto_kdf_keybytes()
-    KDF_CONTEXT_BYTES = crypto_kdf_contextbytes()
-    PWHASH_STR_BYTES  = crypto_pwhash_strbytes()
+    PUBLIC_KEY_SIZE  = crypto_box_publickeybytes()
+    SECRET_KEY_SIZE  = crypto_box_secretkeybytes()
+    NONCE_SIZE       = crypto_box_noncebytes()
+    MAC_SIZE         = crypto_box_macbytes()
+    PUBLIC_SIGN_SIZE = crypto_sign_publickeybytes()
+    SECRET_SIGN_SIZE = crypto_sign_secretkeybytes()
+    SIGNATURE_SIZE   = crypto_sign_bytes()
+    KDF_KEY_SIZE     = crypto_kdf_keybytes()
+    KDF_CONTEXT_SIZE = crypto_kdf_contextbytes()
+    PWHASH_STR_SIZE  = crypto_pwhash_strbytes()
 
     fun crypto_secretbox_easy(
       output               : Pointer(LibC::UChar),
diff --git a/src/cox/nonce.cr b/src/cox/nonce.cr
index 9c1af28..829448f 100644
--- a/src/cox/nonce.cr
+++ b/src/cox/nonce.cr
@@ -5,16 +5,16 @@ module Cox
   class Nonce
     property bytes : Bytes
 
-    NONCE_LENGTH = LibSodium::NONCE_BYTES
+    NONCE_SIZE = LibSodium::NONCE_SIZE
 
     def initialize(@bytes : Bytes)
-      if bytes.bytesize != NONCE_LENGTH
-        raise ArgumentError.new("Nonce must be #{NONCE_LENGTH} bytes, got #{bytes.bytesize}")
+      if bytes.bytesize != NONCE_SIZE
+        raise ArgumentError.new("Nonce must be #{NONCE_SIZE} bytes, got #{bytes.bytesize}")
       end
     end
 
     def self.new
-      new(Random::Secure.random_bytes(NONCE_LENGTH))
+      new(Random::Secure.random_bytes(NONCE_SIZE))
     end
 
     def pointer
diff --git a/src/cox/public_key.cr b/src/cox/public_key.cr
index 982a074..57feaf8 100644
--- a/src/cox/public_key.cr
+++ b/src/cox/public_key.cr
@@ -4,11 +4,11 @@ module Cox
   class PublicKey < Key
     property bytes : Bytes
 
-    KEY_LENGTH = LibSodium::PUBLIC_KEY_BYTES
+    KEY_SIZE = LibSodium::PUBLIC_KEY_SIZE
 
     def initialize(@bytes : Bytes)
-      if bytes.bytesize != KEY_LENGTH
-        raise ArgumentError.new("Public key must be #{KEY_LENGTH} bytes, got #{bytes.bytesize}")
+      if bytes.bytesize != KEY_SIZE
+        raise ArgumentError.new("Public key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
       end
     end
   end
diff --git a/src/cox/pwhash.cr b/src/cox/pwhash.cr
index 944da48..fb933c8 100644
--- a/src/cox/pwhash.cr
+++ b/src/cox/pwhash.cr
@@ -17,7 +17,7 @@ module Cox
     property memlimit = MEMLIMIT_INTERACTIVE
 
     def hash_str(pass)
-      outstr = Bytes.new LibSodium::PWHASH_STR_BYTES
+      outstr = Bytes.new LibSodium::PWHASH_STR_SIZE
       if LibSodium.crypto_pwhash_str(outstr, pass, pass.bytesize, @opslimit, @memlimit) != 0
         raise Cox::Error.new("crypto_pwhash_str")
       end
diff --git a/src/cox/secret_key.cr b/src/cox/secret_key.cr
index bc50276..10960af 100644
--- a/src/cox/secret_key.cr
+++ b/src/cox/secret_key.cr
@@ -4,17 +4,17 @@ module Cox
   class SecretKey < Key
     property bytes : Bytes
 
-    KEY_LENGTH = LibSodium::SECRET_KEY_BYTES
-    MAC_BYTES = LibSodium::MAC_BYTES
+    KEY_SIZE = LibSodium::SECRET_KEY_SIZE
+    MAC_SIZE = LibSodium::MAC_SIZE
 
     def initialize(@bytes : Bytes)
-      if bytes.bytesize != KEY_LENGTH
-        raise ArgumentError.new("Secret key must be #{KEY_LENGTH} bytes, got #{bytes.bytesize}")
+      if bytes.bytesize != KEY_SIZE
+        raise ArgumentError.new("Secret key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
       end
     end
 
     def self.random
-      new Random::Secure.random_bytes(KEY_LENGTH)
+      new Random::Secure.random_bytes(KEY_SIZE)
     end
 
     def encrypt_easy(data)
@@ -32,13 +32,13 @@ module Cox
     end
 
     def encrypt_easy(data : Bytes, nonce : Nonce) : Bytes
-      output = Bytes.new(data.bytesize + MAC_BYTES)
+      output = Bytes.new(data.bytesize + MAC_SIZE)
       encrypt_easy(data, output, nonce)
     end
 
     def encrypt_easy(src : Bytes, dst : Bytes, nonce : Nonce) : Bytes
-      if dst.bytesize != (src.bytesize + MAC_BYTES)
-        raise ArgumentError.new("dst.bytesize must be src.bytesize + MAC_BYTES, got #{dst.bytesize}")
+      if dst.bytesize != (src.bytesize + MAC_SIZE)
+        raise ArgumentError.new("dst.bytesize must be src.bytesize + MAC_SIZE, got #{dst.bytesize}")
       end
       if LibSodium.crypto_secretbox_easy(dst, src, src.bytesize, nonce.pointer, @bytes) != 0
         raise Cox::Error.new("crypto_secretbox_easy")
@@ -47,15 +47,15 @@ module Cox
     end
 
     def decrypt_easy(data : Bytes, nonce : Nonce) : Bytes
-      output_size = data.bytesize - MAC_BYTES
+      output_size = data.bytesize - MAC_SIZE
       raise Cox::DecryptionFailed.new("encrypted data too small #{data.bytesize}") if output_size <= 0
       output = Bytes.new output_size
       decrypt_easy(data, output, nonce)
     end
 
     def decrypt_easy(src : Bytes, dst : Bytes, nonce : Nonce) : Bytes
-      if dst.bytesize != (src.bytesize - MAC_BYTES)
-        raise ArgumentError.new("dst.bytesize must be src.bytesize - MAC_BYTES, got #{dst.bytesize}")
+      if dst.bytesize != (src.bytesize - MAC_SIZE)
+        raise ArgumentError.new("dst.bytesize must be src.bytesize - MAC_SIZE, got #{dst.bytesize}")
       end
       if LibSodium.crypto_secretbox_open_easy(dst, src, src.bytesize, nonce.pointer, @bytes) != 0
         raise Cox::DecryptionFailed.new("crypto_secretbox_easy")
diff --git a/src/cox/sign_key_pair.cr b/src/cox/sign_key_pair.cr
index 0b64882..f58b00e 100644
--- a/src/cox/sign_key_pair.cr
+++ b/src/cox/sign_key_pair.cr
@@ -13,8 +13,8 @@ module Cox
     end
 
     def self.new
-      public_key = Bytes.new(SignPublicKey::KEY_LENGTH)
-      secret_key = Bytes.new(SignSecretKey::KEY_LENGTH)
+      public_key = Bytes.new(SignPublicKey::KEY_SIZE)
+      secret_key = Bytes.new(SignSecretKey::KEY_SIZE)
 
       LibSodium.crypto_sign_keypair(public_key.to_unsafe, secret_key.to_unsafe)
 
diff --git a/src/cox/sign_public_key.cr b/src/cox/sign_public_key.cr
index 030c3c7..64fcfba 100644
--- a/src/cox/sign_public_key.cr
+++ b/src/cox/sign_public_key.cr
@@ -4,11 +4,11 @@ module Cox
   class SignPublicKey < Key
     property bytes : Bytes
 
-    KEY_LENGTH = LibSodium::PUBLIC_SIGN_BYTES
+    KEY_SIZE = LibSodium::PUBLIC_SIGN_SIZE
 
     def initialize(@bytes : Bytes)
-      if bytes.bytesize != KEY_LENGTH
-        raise ArgumentError.new("Public key must be #{KEY_LENGTH} bytes, got #{bytes.bytesize}")
+      if bytes.bytesize != KEY_SIZE
+        raise ArgumentError.new("Public key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
       end
     end
   end
diff --git a/src/cox/sign_secret_key.cr b/src/cox/sign_secret_key.cr
index 332099b..be36c0c 100644
--- a/src/cox/sign_secret_key.cr
+++ b/src/cox/sign_secret_key.cr
@@ -4,11 +4,11 @@ module Cox
   class SignSecretKey < Key
     property bytes : Bytes
 
-    KEY_LENGTH = LibSodium::SECRET_SIGN_BYTES
+    KEY_SIZE = LibSodium::SECRET_SIGN_SIZE
 
     def initialize(@bytes : Bytes)
-      if bytes.bytesize != KEY_LENGTH
-        raise ArgumentError.new("Secret key must be #{KEY_LENGTH} bytes, got #{bytes.bytesize}")
+      if bytes.bytesize != KEY_SIZE
+        raise ArgumentError.new("Secret key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
       end
     end
   end