diff --git a/contracts/utils/Base64Upgradeable.sol b/contracts/utils/Base64Upgradeable.sol
index 2a2ce7750..466af2429 100644
--- a/contracts/utils/Base64Upgradeable.sol
+++ b/contracts/utils/Base64Upgradeable.sol
@@ -5,6 +5,8 @@ pragma solidity ^0.8.0;
 
 /**
  * @dev Provides a set of functions to operate with Base64 strings.
+ *
+ * _Available since v4.5._
  */
 library Base64Upgradeable {
     /**