diff --git a/signer/core/signed_data.go b/signer/core/signed_data.go
index c0da22e62..8ee572f53 100644
--- a/signer/core/signed_data.go
+++ b/signer/core/signed_data.go
@@ -18,6 +18,7 @@ package core
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"mime"
@@ -135,11 +136,7 @@ func (api *SignerAPI) determineSignatureFormat(ctx context.Context, contentType
 		req = &SignDataRequest{ContentType: mediaType, Rawdata: []byte(msg), Messages: messages, Hash: sighash}
 	case apitypes.ApplicationClique.Mime:
 		// Clique is the Ethereum PoA standard
-		stringData, ok := data.(string)
-		if !ok {
-			return nil, useEthereumV, fmt.Errorf("input for %v must be an hex-encoded string", apitypes.ApplicationClique.Mime)
-		}
-		cliqueData, err := hexutil.Decode(stringData)
+		cliqueData, err := fromHex(data)
 		if err != nil {
 			return nil, useEthereumV, err
 		}
@@ -167,27 +164,30 @@ func (api *SignerAPI) determineSignatureFormat(ctx context.Context, contentType
 		// Clique uses V on the form 0 or 1
 		useEthereumV = false
 		req = &SignDataRequest{ContentType: mediaType, Rawdata: cliqueRlp, Messages: messages, Hash: sighash}
+	case apitypes.DataTyped.Mime:
+		// EIP-712 conformant typed data
+		var err error
+		req, err = typedDataRequest(data)
+		if err != nil {
+			return nil, useEthereumV, err
+		}
 	default: // also case TextPlain.Mime:
 		// Calculates an Ethereum ECDSA signature for:
 		// hash = keccak256("\x19Ethereum Signed Message:\n${message length}${message}")
-		// We expect it to be a string
-		if stringData, ok := data.(string); !ok {
-			return nil, useEthereumV, fmt.Errorf("input for text/plain must be an hex-encoded string")
-		} else {
-			if textData, err := hexutil.Decode(stringData); err != nil {
-				return nil, useEthereumV, err
-			} else {
-				sighash, msg := accounts.TextAndHash(textData)
-				messages := []*apitypes.NameValueType{
-					{
-						Name:  "message",
-						Typ:   accounts.MimetypeTextPlain,
-						Value: msg,
-					},
-				}
-				req = &SignDataRequest{ContentType: mediaType, Rawdata: []byte(msg), Messages: messages, Hash: sighash}
-			}
+		// We expect input to be a hex-encoded string
+		textData, err := fromHex(data)
+		if err != nil {
+			return nil, useEthereumV, err
 		}
+		sighash, msg := accounts.TextAndHash(textData)
+		messages := []*apitypes.NameValueType{
+			{
+				Name:  "message",
+				Typ:   accounts.MimetypeTextPlain,
+				Value: msg,
+			},
+		}
+		req = &SignDataRequest{ContentType: mediaType, Rawdata: []byte(msg), Messages: messages, Hash: sighash}
 	}
 	req.Address = addr
 	req.Meta = MetadataFromContext(ctx)
@@ -233,20 +233,12 @@ func (api *SignerAPI) SignTypedData(ctx context.Context, addr common.MixedcaseAd
 // - the signature preimage (hash)
 func (api *SignerAPI) signTypedData(ctx context.Context, addr common.MixedcaseAddress,
 	typedData apitypes.TypedData, validationMessages *apitypes.ValidationMessages) (hexutil.Bytes, hexutil.Bytes, error) {
-	sighash, rawData, err := apitypes.TypedDataAndHash(typedData)
+	req, err := typedDataRequest(typedData)
 	if err != nil {
 		return nil, nil, err
 	}
-	messages, err := typedData.Format()
-	if err != nil {
-		return nil, nil, err
-	}
-	req := &SignDataRequest{
-		ContentType: apitypes.DataTyped.Mime,
-		Rawdata:     []byte(rawData),
-		Messages:    messages,
-		Hash:        sighash,
-		Address:     addr}
+	req.Address = addr
+	req.Meta = MetadataFromContext(ctx)
 	if validationMessages != nil {
 		req.Callinfo = validationMessages.Messages
 	}
@@ -255,7 +247,46 @@ func (api *SignerAPI) signTypedData(ctx context.Context, addr common.MixedcaseAd
 		api.UI.ShowError(err.Error())
 		return nil, nil, err
 	}
-	return signature, sighash, nil
+	return signature, req.Hash, nil
+}
+
+// fromHex tries to interpret the data as type string, and convert from
+// hexadecimal to []byte
+func fromHex(data any) ([]byte, error) {
+	if stringData, ok := data.(string); ok {
+		binary, err := hexutil.Decode(stringData)
+		return binary, err
+	}
+	return nil, fmt.Errorf("wrong type %T", data)
+}
+
+// typeDataRequest tries to convert the data into a SignDataRequest.
+func typedDataRequest(data any) (*SignDataRequest, error) {
+	var typedData apitypes.TypedData
+	if td, ok := data.(apitypes.TypedData); ok {
+		typedData = td
+	} else { // Hex-encoded data
+		jsonData, err := fromHex(data)
+		if err != nil {
+			return nil, err
+		}
+		if err = json.Unmarshal(jsonData, &typedData); err != nil {
+			return nil, err
+		}
+	}
+	messages, err := typedData.Format()
+	if err != nil {
+		return nil, err
+	}
+	sighash, rawData, err := apitypes.TypedDataAndHash(typedData)
+	if err != nil {
+		return nil, err
+	}
+	return &SignDataRequest{
+		ContentType: apitypes.DataTyped.Mime,
+		Rawdata:     []byte(rawData),
+		Messages:    messages,
+		Hash:        sighash}, nil
 }
 
 // EcRecover recovers the address associated with the given sig.
@@ -293,30 +324,20 @@ func UnmarshalValidatorData(data interface{}) (apitypes.ValidatorData, error) {
 	if !ok {
 		return apitypes.ValidatorData{}, errors.New("validator input is not a map[string]interface{}")
 	}
-	addr, ok := raw["address"].(string)
-	if !ok {
-		return apitypes.ValidatorData{}, errors.New("validator address is not sent as a string")
-	}
-	addrBytes, err := hexutil.Decode(addr)
+	addrBytes, err := fromHex(raw["address"])
 	if err != nil {
-		return apitypes.ValidatorData{}, err
+		return apitypes.ValidatorData{}, fmt.Errorf("validator address error: %w", err)
 	}
-	if !ok || len(addrBytes) == 0 {
+	if len(addrBytes) == 0 {
 		return apitypes.ValidatorData{}, errors.New("validator address is undefined")
 	}
-
-	message, ok := raw["message"].(string)
-	if !ok {
-		return apitypes.ValidatorData{}, errors.New("message is not sent as a string")
-	}
-	messageBytes, err := hexutil.Decode(message)
+	messageBytes, err := fromHex(raw["message"])
 	if err != nil {
-		return apitypes.ValidatorData{}, err
+		return apitypes.ValidatorData{}, fmt.Errorf("message error: %w", err)
 	}
-	if !ok || len(messageBytes) == 0 {
+	if len(messageBytes) == 0 {
 		return apitypes.ValidatorData{}, errors.New("message is undefined")
 	}
-
 	return apitypes.ValidatorData{
 		Address: common.BytesToAddress(addrBytes),
 		Message: messageBytes,
diff --git a/signer/core/signed_data_test.go b/signer/core/signed_data_test.go
index 7d5661e7e..8deff919c 100644
--- a/signer/core/signed_data_test.go
+++ b/signer/core/signed_data_test.go
@@ -220,15 +220,29 @@ func TestSignData(t *testing.T) {
 	if signature == nil || len(signature) != 65 {
 		t.Errorf("Expected 65 byte signature (got %d bytes)", len(signature))
 	}
-	// data/typed
+	// data/typed via SignTypeData
 	control.approveCh <- "Y"
 	control.inputCh <- "a_long_password"
-	signature, err = api.SignTypedData(context.Background(), a, typedData)
-	if err != nil {
+	var want []byte
+	if signature, err = api.SignTypedData(context.Background(), a, typedData); err != nil {
 		t.Fatal(err)
-	}
-	if signature == nil || len(signature) != 65 {
+	} else if signature == nil || len(signature) != 65 {
 		t.Errorf("Expected 65 byte signature (got %d bytes)", len(signature))
+	} else {
+		want = signature
+	}
+
+	// data/typed via SignData / mimetype typed data
+	control.approveCh <- "Y"
+	control.inputCh <- "a_long_password"
+	if typedDataJson, err := json.Marshal(typedData); err != nil {
+		t.Fatal(err)
+	} else if signature, err = api.SignData(context.Background(), apitypes.DataTyped.Mime, a, hexutil.Encode(typedDataJson)); err != nil {
+		t.Fatal(err)
+	} else if signature == nil || len(signature) != 65 {
+		t.Errorf("Expected 65 byte signature (got %d bytes)", len(signature))
+	} else if have := signature; !bytes.Equal(have, want) {
+		t.Fatalf("want %x, have %x", want, have)
 	}
 }