diff --git a/ledger/allegra/rules_test.go b/ledger/allegra/rules_test.go
index 1f2dc283..d24ee4ca 100644
--- a/ledger/allegra/rules_test.go
+++ b/ledger/allegra/rules_test.go
@@ -17,7 +17,7 @@ package allegra_test
 import (
 	"crypto/rand"
 	"encoding/hex"
-	"fmt"
+	"errors"
 	"testing"
 
 	"github.com/blinklabs-io/gouroboros/ledger/allegra"
@@ -48,7 +48,7 @@ func (ls testLedgerState) UtxoById(
 		}
 		return tmpUtxo, nil
 	}
-	return common.Utxo{}, fmt.Errorf("not found")
+	return common.Utxo{}, errors.New("not found")
 }
 
 func TestUtxoValidateOutsideValidityIntervalUtxo(t *testing.T) {
diff --git a/ledger/mary/rules_test.go b/ledger/mary/rules_test.go
index f6ba0a3e..ce8ac5b8 100644
--- a/ledger/mary/rules_test.go
+++ b/ledger/mary/rules_test.go
@@ -17,7 +17,7 @@ package mary_test
 import (
 	"crypto/rand"
 	"encoding/hex"
-	"fmt"
+	"errors"
 	"testing"
 
 	"github.com/blinklabs-io/gouroboros/cbor"
@@ -50,7 +50,7 @@ func (ls testLedgerState) UtxoById(
 		}
 		return tmpUtxo, nil
 	}
-	return common.Utxo{}, fmt.Errorf("not found")
+	return common.Utxo{}, errors.New("not found")
 }
 
 func TestUtxoValidateOutsideValidityIntervalUtxo(t *testing.T) {
diff --git a/ledger/shelley/rules_test.go b/ledger/shelley/rules_test.go
index 030cfc87..736ab163 100644
--- a/ledger/shelley/rules_test.go
+++ b/ledger/shelley/rules_test.go
@@ -17,7 +17,7 @@ package shelley_test
 import (
 	"crypto/rand"
 	"encoding/hex"
-	"fmt"
+	"errors"
 	"testing"
 
 	"github.com/blinklabs-io/gouroboros/ledger/common"
@@ -47,7 +47,7 @@ func (ls testLedgerState) UtxoById(
 		}
 		return tmpUtxo, nil
 	}
-	return common.Utxo{}, fmt.Errorf("not found")
+	return common.Utxo{}, errors.New("not found")
 }
 
 func TestUtxoValidateTimeToLive(t *testing.T) {
diff --git a/protocol/handshake/client_test.go b/protocol/handshake/client_test.go
index 2baea06a..edf9cfe2 100644
--- a/protocol/handshake/client_test.go
+++ b/protocol/handshake/client_test.go
@@ -248,7 +248,7 @@ func TestClientNtNAcceptV11(t *testing.T) {
 
 func TestClientNtCRefuseVersionMismatch(t *testing.T) {
 	defer goleak.VerifyNone(t)
-	expectedErr := fmt.Sprintf("%s: version mismatch", handshake.ProtocolName)
+	expectedErr := handshake.ProtocolName + ": version mismatch"
 	mockConn := ouroboros_mock.NewConnection(
 		ouroboros_mock.ProtocolRoleClient,
 		[]ouroboros_mock.ConversationEntry{
@@ -282,7 +282,7 @@ func TestClientNtCRefuseVersionMismatch(t *testing.T) {
 
 func TestClientNtCRefuseDecodeError(t *testing.T) {
 	defer goleak.VerifyNone(t)
-	expectedErr := fmt.Sprintf("%s: decode error: foo", handshake.ProtocolName)
+	expectedErr := handshake.ProtocolName + ": decode error: foo"
 	mockConn := ouroboros_mock.NewConnection(
 		ouroboros_mock.ProtocolRoleClient,
 		[]ouroboros_mock.ConversationEntry{
@@ -317,7 +317,7 @@ func TestClientNtCRefuseDecodeError(t *testing.T) {
 
 func TestClientNtCRefuseRefused(t *testing.T) {
 	defer goleak.VerifyNone(t)
-	expectedErr := fmt.Sprintf("%s: refused: foo", handshake.ProtocolName)
+	expectedErr := handshake.ProtocolName + ": refused: foo"
 	mockConn := ouroboros_mock.NewConnection(
 		ouroboros_mock.ProtocolRoleClient,
 		[]ouroboros_mock.ConversationEntry{
diff --git a/protocol/handshake/server_test.go b/protocol/handshake/server_test.go
index f3692144..998e103a 100644
--- a/protocol/handshake/server_test.go
+++ b/protocol/handshake/server_test.go
@@ -1,4 +1,4 @@
-// Copyright 2023 Blink Labs Software
+// Copyright 2025 Blink Labs Software
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
 package handshake_test
 
 import (
+	"errors"
 	"fmt"
 	"testing"
 	"time"
@@ -97,9 +98,7 @@ func TestServerHandshakeRefuseVersionMismatch(t *testing.T) {
 	defer func() {
 		goleak.VerifyNone(t)
 	}()
-	expectedErr := fmt.Errorf(
-		"handshake failed: refused due to version mismatch",
-	)
+	expectedErr := errors.New("handshake failed: refused due to version mismatch")
 	mockConn := ouroboros_mock.NewConnection(
 		ouroboros_mock.ProtocolRoleServer,
 		[]ouroboros_mock.ConversationEntry{
diff --git a/protocol/keepalive/client_test.go b/protocol/keepalive/client_test.go
index dda2004b..85a7e075 100644
--- a/protocol/keepalive/client_test.go
+++ b/protocol/keepalive/client_test.go
@@ -1,4 +1,4 @@
-// Copyright 2023 Blink Labs Software
+// Copyright 2025 Blink Labs Software
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
 package keepalive_test
 
 import (
+	"errors"
 	"fmt"
 	"testing"
 	"time"
@@ -142,7 +143,7 @@ func TestServerKeepaliveHandlingWithWrongResponse(t *testing.T) {
 	go func() {
 		err := <-mockConn.ErrorChan()
 		if err == nil {
-			asyncErrChan <- fmt.Errorf("did not receive expected error")
+			asyncErrChan <- errors.New("did not receive expected error")
 		} else {
 			if err.Error() != expectedErr {
 				asyncErrChan <- fmt.Errorf("did not receive expected error\n  got:    %s\n  wanted: %s", err, expectedErr)
diff --git a/protocol/localtxsubmission/client_test.go b/protocol/localtxsubmission/client_test.go
index 63dcdaed..6c038395 100644
--- a/protocol/localtxsubmission/client_test.go
+++ b/protocol/localtxsubmission/client_test.go
@@ -1,4 +1,4 @@
-// Copyright 2024 Blink Labs Software
+// Copyright 2025 Blink Labs Software
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
 package localtxsubmission_test
 
 import (
+	"errors"
 	"fmt"
 	"testing"
 	"time"
@@ -129,7 +130,7 @@ func TestSubmitTxRject(t *testing.T) {
 	expectedErr := localtxsubmission.TransactionRejectedError{
 		// [0, [1, ["foo"]]]
 		ReasonCbor: test.DecodeHexString("820082018163666f6f"),
-		Reason:     fmt.Errorf("GenericError ([0 [1 [foo]]])"),
+		Reason:     errors.New("GenericError ([0 [1 [foo]]])"),
 	}
 	conversation := append(
 		conversationHandshakeSubmitTx,