diff --git a/README.md b/README.md
index 546fa4e..bce1562 100644
--- a/README.md
+++ b/README.md
@@ -154,11 +154,11 @@ function evolved.alive_any(...) end
 Sometimes (for debugging purposes, for example), it is necessary to extract the index and version from an identifier or to pack them back into an identifier. The [`evolved.pack`](#evolvedpack) and [`evolved.unpack`](#evolvedunpack) functions can be used for this purpose.
 
 ```lua
----@param index integer
----@param version integer
+---@param primary integer
+---@param secondary integer
 ---@return evolved.id id
 ---@nodiscard
-function evolved.pack(index, version) end
+function evolved.pack(primary, secondary) end
 
 ---@param id evolved.id
 ---@return integer primary
@@ -1409,11 +1409,11 @@ function evolved.name(...) end
 ### `evolved.pack`
 
 ```lua
----@param index integer
----@param version integer
+---@param primary integer
+---@param secondary integer
 ---@return evolved.id id
 ---@nodiscard
-function evolved.pack(index, version) end
+function evolved.pack(primary, secondary) end
 ```
 
 ### `evolved.unpack`
diff --git a/evolved.lua b/evolved.lua
index 971d497..6352248 100644
--- a/evolved.lua
+++ b/evolved.lua
@@ -4789,20 +4789,20 @@ function __evolved_name(...)
     end
 end
 
----@param index integer
----@param version integer
+---@param primary integer
+---@param secondary integer
 ---@return evolved.id id
 ---@nodiscard
-function __evolved_pack(index, version)
-    if index < 1 or index > 2 ^ 20 - 1 then
-        __error_fmt('the index (%d) is out of range [1, 2 ^ 20 - 1]', index)
+function __evolved_pack(primary, secondary)
+    if primary < 1 or primary > 2 ^ 20 - 1 then
+        __error_fmt('the primary (%d) is out of range [1, 2 ^ 20 - 1]', primary)
     end
 
-    if version < 1 or version > 2 ^ 20 - 1 then
-        __error_fmt('the version (%d) is out of range [1, 2 ^ 20 - 1]', version)
+    if secondary < 1 or secondary > 2 ^ 20 - 1 then
+        __error_fmt('the secondary (%d) is out of range [1, 2 ^ 20 - 1]', secondary)
     end
 
-    return index + version * 2 ^ 20 --[[@as evolved.id]]
+    return primary + secondary * 2 ^ 20 --[[@as evolved.id]]
 end
 
 ---@param id evolved.id