diff --git a/nats.go b/nats.go
index 988924d24..5edbdd3d3 100644
--- a/nats.go
+++ b/nats.go
@@ -2323,6 +2323,19 @@ func normalizeErr(line string) string {
 	return s
 }
 
+// natsProtoErr represents an -ERR protocol message sent by the server.
+type natsProtoErr struct {
+	description string
+}
+
+func (nerr *natsProtoErr) Error() string {
+	return fmt.Sprintf("nats: %s", nerr.description)
+}
+
+func (nerr *natsProtoErr) Is(err error) bool {
+	return strings.ToLower(nerr.Error()) == err.Error()
+}
+
 // Send a connect protocol message to the server, issue user/password if
 // applicable. Will wait for a flush to return from the server for error
 // processing.
@@ -2377,8 +2390,7 @@ func (nc *Conn) sendConnect() error {
 				// in doReconnect()).
 				nc.processAuthError(authErr)
 			}
-
-			return errors.New("nats: " + proto)
+			return &natsProtoErr{proto}
 		}
 
 		// Notify that we got an unexpected protocol.
diff --git a/test/auth_test.go b/test/auth_test.go
index 27559a750..32d80e5b4 100644
--- a/test/auth_test.go
+++ b/test/auth_test.go
@@ -14,6 +14,7 @@
 package test
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"sync/atomic"
@@ -44,6 +45,10 @@ func TestAuth(t *testing.T) {
 		t.Fatalf("Expected error '%v', got '%v'", nats.ErrAuthorization, err)
 	}
 
+	if !errors.Is(err, nats.ErrAuthorization) {
+		t.Fatalf("Expected error '%v', got '%v'", nats.ErrAuthorization, err)
+	}
+
 	nc, err := nats.Connect("nats://derek:foo@127.0.0.1:8232")
 	if err != nil {
 		t.Fatal("Should have connected successfully with a token")
diff --git a/test/cluster_test.go b/test/cluster_test.go
index bbe3b9075..5f7595f98 100644
--- a/test/cluster_test.go
+++ b/test/cluster_test.go
@@ -14,6 +14,7 @@
 package test
 
 import (
+	"errors"
 	"fmt"
 	"math"
 	"net"
@@ -193,6 +194,10 @@ func TestAuthServers(t *testing.T) {
 		t.Fatalf("Wrong error, wanted Auth failure, got '%s'\n", err)
 	}
 
+	if !errors.Is(err, nats.ErrAuthorization) {
+		t.Fatalf("Expected error '%v', got '%v'", nats.ErrAuthorization, err)
+	}
+
 	// Test that we can connect to a subsequent correct server.
 	var authServers = []string{
 		"nats://127.0.0.1:1222",