diff --git a/src/contracts/mocks/nf-token-metadata-enumerable-mock.sol b/src/contracts/mocks/nf-token-metadata-enumerable-mock.sol
index 54003da..6f2b8c8 100644
--- a/src/contracts/mocks/nf-token-metadata-enumerable-mock.sol
+++ b/src/contracts/mocks/nf-token-metadata-enumerable-mock.sol
@@ -15,6 +15,29 @@ contract NFTokenMetadataEnumerableMock is
   Ownable
 {
 
+  /**
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param _interfaceID Id of the interface.
+   * @return True if _interfaceID is supported, false otherwise.
+   */
+  function supportsInterface(
+    bytes4 _interfaceID
+  )
+    external
+    override(NFTokenEnumerable, NFTokenMetadata)
+    virtual
+    pure
+    returns (bool)
+  {
+    if (_interfaceID == 0x01ffc9a7
+      || _interfaceID == 0x80ac58cd
+      || _interfaceID == 0x780e9d63
+      || _interfaceID == 0x5b5e139f) {
+      return true;
+    }
+    return false;
+  }
+
   /**
    * @dev Contract constructor.
    * @param _name A descriptive name for a collection of NFTs.
diff --git a/src/contracts/tokens/nf-token-enumerable.sol b/src/contracts/tokens/nf-token-enumerable.sol
index 25118bc..ac73d0f 100644
--- a/src/contracts/tokens/nf-token-enumerable.sol
+++ b/src/contracts/tokens/nf-token-enumerable.sol
@@ -38,14 +38,6 @@ contract NFTokenEnumerable is
    */
   mapping(uint256 => uint256) internal idToOwnerIndex;
 
-  /**
-   * @dev Contract constructor.
-   */
-  constructor()
-  {
-    supportedInterfaces[0x780e9d63] = true; // ERC721Enumerable
-  }
-
   /**
    * @dev Returns the count of all existing NFTokens.
    * @return Total supply of NFTs.
@@ -95,6 +87,28 @@ contract NFTokenEnumerable is
     return ownerToIds[_owner][_index];
   }
 
+    /**
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param _interfaceID Id of the interface.
+   * @return True if _interfaceID is supported, false otherwise.
+   */
+  function supportsInterface(
+    bytes4 _interfaceID
+  )
+    external
+    override
+    virtual
+    pure
+    returns (bool)
+  {
+    if (_interfaceID == 0x01ffc9a7
+      || _interfaceID == 0x80ac58cd
+      || _interfaceID == 0x780e9d63) {
+      return true;
+    }
+    return false;
+  }
+
   /**
    * @notice This is an internal function which should be called from user-implemented external
    * mint function. Its purpose is to show and properly initialize data structures when using this
diff --git a/src/contracts/tokens/nf-token-metadata.sol b/src/contracts/tokens/nf-token-metadata.sol
index bd8dced..f89945f 100644
--- a/src/contracts/tokens/nf-token-metadata.sol
+++ b/src/contracts/tokens/nf-token-metadata.sol
@@ -27,15 +27,6 @@ contract NFTokenMetadata is
    */
   mapping (uint256 => string) internal idToUri;
 
-  /**
-   * @notice When implementing this contract don't forget to set nftName and nftSymbol.
-   * @dev Contract constructor.
-   */
-  constructor()
-  {
-    supportedInterfaces[0x5b5e139f] = true; // ERC721Metadata
-  }
-
   /**
    * @dev Returns a descriptive name for a collection of NFTokens.
    * @return _name Representing name.
@@ -96,6 +87,28 @@ contract NFTokenMetadata is
     return idToUri[_tokenId];
   }
 
+  /**
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param _interfaceID Id of the interface.
+   * @return True if _interfaceID is supported, false otherwise.
+   */
+  function supportsInterface(
+    bytes4 _interfaceID
+  )
+    external
+    override
+    virtual
+    pure
+    returns (bool)
+  {
+    if (_interfaceID == 0x01ffc9a7
+      || _interfaceID == 0x80ac58cd
+      || _interfaceID == 0x5b5e139f) {
+      return true;
+    }
+    return false;
+  }
+
   /**
    * @notice This is an internal function which should be called from user-implemented external
    * burn function. Its purpose is to show and properly initialize data structures when using this
diff --git a/src/contracts/tokens/nf-token.sol b/src/contracts/tokens/nf-token.sol
index fd6dc54..9674e2b 100644
--- a/src/contracts/tokens/nf-token.sol
+++ b/src/contracts/tokens/nf-token.sol
@@ -3,7 +3,7 @@ pragma solidity ^0.8.0;
 
 import "./erc721.sol";
 import "./erc721-token-receiver.sol";
-import "../utils/supports-interface.sol";
+import "../utils/erc165.sol";
 import "../utils/address-utils.sol";
 
 /**
@@ -11,7 +11,7 @@ import "../utils/address-utils.sol";
  */
 contract NFToken is
   ERC721,
-  SupportsInterface
+  ERC165
 {
   using AddressUtils for address;
 
@@ -100,14 +100,6 @@ contract NFToken is
     _;
   }
 
-  /**
-   * @dev Contract constructor.
-   */
-  constructor()
-  {
-    supportedInterfaces[0x80ac58cd] = true; // ERC721
-  }
-
   /**
    * @notice Throws unless `msg.sender` is the current owner, an authorized operator, or the
    * approved address for this NFT. Throws if `_from` is not the current owner. Throws if `_to` is
@@ -294,6 +286,26 @@ contract NFToken is
     return ownerToOperators[_owner][_operator];
   }
 
+  /**
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param _interfaceID Id of the interface.
+   * @return True if _interfaceID is supported, false otherwise.
+   */
+  function supportsInterface(
+    bytes4 _interfaceID
+  )
+    external
+    override
+    virtual
+    pure
+    returns (bool)
+  {
+    if (_interfaceID == 0x01ffc9a7 || _interfaceID == 0x80ac58cd) {
+      return true;
+    }
+    return false;
+  }
+
   /**
    * @notice Does NO checks.
    * @dev Actually performs the transfer.
diff --git a/src/contracts/utils/erc165.sol b/src/contracts/utils/erc165.sol
index 5c70dd6..2babd39 100644
--- a/src/contracts/utils/erc165.sol
+++ b/src/contracts/utils/erc165.sol
@@ -18,7 +18,7 @@ interface ERC165
     bytes4 _interfaceID
   )
     external
-    view
+    pure
     returns (bool);
     
 }
diff --git a/src/contracts/utils/supports-interface.sol b/src/contracts/utils/supports-interface.sol
deleted file mode 100644
index ced307f..0000000
--- a/src/contracts/utils/supports-interface.sol
+++ /dev/null
@@ -1,42 +0,0 @@
-// SPDX-License-Identifier: MIT
-pragma solidity ^0.8.0;
-
-import "./erc165.sol";
-
-/**
- * @dev Implementation of standard for detect smart contract interfaces.
- */
-contract SupportsInterface is
-  ERC165
-{
-
-  /**
-   * @dev Mapping of supported intefraces. You must not set element 0xffffffff to true.
-   */
-  mapping(bytes4 => bool) internal supportedInterfaces;
-
-  /**
-   * @dev Contract constructor.
-   */
-  constructor()
-  {
-    supportedInterfaces[0x01ffc9a7] = true; // ERC165
-  }
-
-  /**
-   * @dev Function to check which interfaces are suported by this contract.
-   * @param _interfaceID Id of the interface.
-   * @return True if _interfaceID is supported, false otherwise.
-   */
-  function supportsInterface(
-    bytes4 _interfaceID
-  )
-    external
-    override
-    view
-    returns (bool)
-  {
-    return supportedInterfaces[_interfaceID];
-  }
-
-}