diff --git a/src/interfaces/IB20Factory.sol b/src/interfaces/IB20Factory.sol
index ff03131..6d5c1c4 100644
--- a/src/interfaces/IB20Factory.sol
+++ b/src/interfaces/IB20Factory.sol
@@ -181,9 +181,9 @@ interface IB20Factory {
     ///         any known encoding for the requested variant.
     error UnsupportedVersion(uint8 version, B20Variant variant);
 
-    /// @notice A required string argument was the empty string (e.g.
-    ///         security `isin`).
-    error MissingRequiredField();
+    /// @notice A required string argument was the empty string.
+    /// @param field  Name of the missing field (e.g. `"isin"`, `"currency"`).
+    error MissingRequiredField(string field);
 
     /// @notice The stablecoin `currency` contained a non-`A`–`Z` byte.
     error InvalidCurrency(string code);
diff --git a/test/lib/mocks/MockB20Factory.sol b/test/lib/mocks/MockB20Factory.sol
index 7cdec8f..26caaa7 100644
--- a/test/lib/mocks/MockB20Factory.sol
+++ b/test/lib/mocks/MockB20Factory.sol
@@ -119,6 +119,8 @@ contract MockB20Factory is IB20Factory {
             if (p.version != B20FactoryLib.B20_STABLECOIN_CREATE_PARAMS_VERSION) {
                 revert UnsupportedVersion(p.version, variant);
             }
+            // Required: currency must be non-empty.
+            if (bytes(p.currency).length == 0) revert MissingRequiredField("currency");
             // Format check: every byte must be an uppercase ASCII letter (A-Z).
             bytes memory cb = bytes(p.currency);
             for (uint256 i = 0; i < cb.length; ++i) {
@@ -134,7 +136,7 @@ contract MockB20Factory is IB20Factory {
             if (p.version != B20FactoryLib.B20_SECURITY_CREATE_PARAMS_VERSION) {
                 revert UnsupportedVersion(p.version, variant);
             }
-            if (bytes(p.isin).length == 0) revert MissingRequiredField();
+            if (bytes(p.isin).length == 0) revert MissingRequiredField("isin");
             name_ = p.name;
             symbol_ = p.symbol;
             admin = p.initialAdmin;
diff --git a/test/unit/B20Factory/createToken.t.sol b/test/unit/B20Factory/createToken.t.sol
index 30fed40..af2703b 100644
--- a/test/unit/B20Factory/createToken.t.sol
+++ b/test/unit/B20Factory/createToken.t.sol
@@ -126,16 +126,24 @@ contract B20FactoryCreateB20Test is B20FactoryTest {
         factory.createB20(IB20Factory.B20Variant.SECURITY, salt, abi.encode(p), new bytes[](0));
     }
 
-    /// @notice Verifies security createToken reverts when isin is the empty string
-    /// @dev Per-variant required-field check; checks MissingRequiredField() error
+    /// @notice Verifies security createToken reverts with the field name when isin is the empty string.
     function test_createB20_revert_missingIsin(address caller, bytes32 salt) public {
         _assumeValidCaller(caller);
         IB20Factory.B20SecurityCreateParams memory p = _securityParams("Security Test", "SEC", admin, "", 0);
         vm.prank(caller);
-        vm.expectRevert(IB20Factory.MissingRequiredField.selector);
+        vm.expectRevert(abi.encodeWithSelector(IB20Factory.MissingRequiredField.selector, "isin"));
         factory.createB20(IB20Factory.B20Variant.SECURITY, salt, abi.encode(p), new bytes[](0));
     }
 
+    /// @notice Verifies stablecoin createToken reverts with the field name when currency is the empty string.
+    function test_createB20_revert_missingCurrency(address caller, bytes32 salt) public {
+        _assumeValidCaller(caller);
+        IB20Factory.B20StablecoinCreateParams memory p = _stablecoinParams("Stablecoin Test", "SCT", admin, "");
+        vm.prank(caller);
+        vm.expectRevert(abi.encodeWithSelector(IB20Factory.MissingRequiredField.selector, "currency"));
+        factory.createB20(IB20Factory.B20Variant.STABLECOIN, salt, abi.encode(p), new bytes[](0));
+    }
+
     /// @notice Verifies createToken reverts when (variant, sender, salt) collides
     /// @dev Deterministic-address uniqueness; checks TokenAlreadyExists(token) error
     function test_createB20_revert_tokenAlreadyExists(address caller, bytes32 salt) public {