diff --git a/acme/api/order.go b/acme/api/order.go
index 679fe32f..2927a620 100644
--- a/acme/api/order.go
+++ b/acme/api/order.go
@@ -13,6 +13,7 @@ import (
 	"github.com/go-chi/chi"
 
 	"go.step.sm/crypto/randutil"
+	"go.step.sm/crypto/x509util"
 
 	"github.com/smallstep/certificates/acme"
 	"github.com/smallstep/certificates/api/render"
@@ -33,12 +34,20 @@ func (n *NewOrderRequest) Validate() error {
 		return acme.NewError(acme.ErrorMalformedType, "identifiers list cannot be empty")
 	}
 	for _, id := range n.Identifiers {
-		if !(id.Type == acme.DNS || id.Type == acme.IP) {
+		switch id.Type {
+		case acme.IP:
+			if net.ParseIP(id.Value) == nil {
+				return acme.NewError(acme.ErrorMalformedType, "invalid IP address: %s", id.Value)
+			}
+		case acme.DNS:
+			value, _ := trimIfWildcard(id.Value)
+			if _, err := x509util.SanitizeName(value); err != nil {
+				return acme.NewError(acme.ErrorMalformedType, "invalid DNS name: %s", id.Value)
+			}
+		default:
 			return acme.NewError(acme.ErrorMalformedType, "identifier type unsupported: %s", id.Type)
 		}
-		if id.Type == acme.IP && net.ParseIP(id.Value) == nil {
-			return acme.NewError(acme.ErrorMalformedType, "invalid IP address: %s", id.Value)
-		}
+
 		// TODO(hs): add some validations for DNS domains?
 		// TODO(hs): combine the errors from this with allow/deny policy, like example error in https://datatracker.ietf.org/doc/html/rfc8555#section-6.7.1
 	}
@@ -218,13 +227,19 @@ func newACMEPolicyEngine(eak *acme.ExternalAccountKey) (policy.X509Policy, error
 	return policy.NewX509PolicyEngine(eak.Policy)
 }
 
+func trimIfWildcard(value string) (string, bool) {
+	if strings.HasPrefix(value, "*.") {
+		return strings.TrimPrefix(value, "*."), true
+	}
+	return value, false
+}
+
 func newAuthorization(ctx context.Context, az *acme.Authorization) error {
-	if strings.HasPrefix(az.Identifier.Value, "*.") {
-		az.Wildcard = true
-		az.Identifier = acme.Identifier{
-			Value: strings.TrimPrefix(az.Identifier.Value, "*."),
-			Type:  az.Identifier.Type,
-		}
+	value, isWildcard := trimIfWildcard(az.Identifier.Value)
+	az.Wildcard = isWildcard
+	az.Identifier = acme.Identifier{
+		Value: value,
+		Type:  az.Identifier.Type,
 	}
 
 	chTypes := challengeTypes(az)
diff --git a/acme/api/order_test.go b/acme/api/order_test.go
index 7f67c72e..724357d8 100644
--- a/acme/api/order_test.go
+++ b/acme/api/order_test.go
@@ -49,6 +49,36 @@ func TestNewOrderRequest_Validate(t *testing.T) {
 				err: acme.NewError(acme.ErrorMalformedType, "identifier type unsupported: foo"),
 			}
 		},
+		"fail/bad-identifier/bad-dns": func(t *testing.T) test {
+			return test{
+				nor: &NewOrderRequest{
+					Identifiers: []acme.Identifier{
+						{Type: "dns", Value: "xn--bücher.example.com"},
+					},
+				},
+				err: acme.NewError(acme.ErrorMalformedType, "invalid DNS name: xn--bücher.example.com"),
+			}
+		},
+		"fail/bad-identifier/dns-port": func(t *testing.T) test {
+			return test{
+				nor: &NewOrderRequest{
+					Identifiers: []acme.Identifier{
+						{Type: "dns", Value: "example.com:8080"},
+					},
+				},
+				err: acme.NewError(acme.ErrorMalformedType, "invalid DNS name: example.com:8080"),
+			}
+		},
+		"fail/bad-identifier/dns-wildcard-port": func(t *testing.T) test {
+			return test{
+				nor: &NewOrderRequest{
+					Identifiers: []acme.Identifier{
+						{Type: "dns", Value: "*.example.com:8080"},
+					},
+				},
+				err: acme.NewError(acme.ErrorMalformedType, "invalid DNS name: *.example.com:8080"),
+			}
+		},
 		"fail/bad-ip": func(t *testing.T) test {
 			nbf := time.Now().UTC().Add(time.Minute)
 			naf := time.Now().UTC().Add(5 * time.Minute)
@@ -72,7 +102,7 @@ func TestNewOrderRequest_Validate(t *testing.T) {
 				nor: &NewOrderRequest{
 					Identifiers: []acme.Identifier{
 						{Type: "dns", Value: "example.com"},
-						{Type: "dns", Value: "bar.com"},
+						{Type: "dns", Value: "*.bar.com"},
 					},
 					NotAfter:  naf,
 					NotBefore: nbf,
@@ -2097,3 +2127,32 @@ func TestHandler_challengeTypes(t *testing.T) {
 		})
 	}
 }
+
+func TestTrimIfWildcard(t *testing.T) {
+	tests := []struct {
+		name      string
+		arg       string
+		wantValue string
+		wantBool  bool
+	}{
+		{
+			name:      "no trim",
+			arg:       "smallstep.com",
+			wantValue: "smallstep.com",
+			wantBool:  false,
+		},
+		{
+			name:      "trim",
+			arg:       "*.smallstep.com",
+			wantValue: "smallstep.com",
+			wantBool:  true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			v, ok := trimIfWildcard(tt.arg)
+			assert.Equals(t, v, tt.wantValue)
+			assert.Equals(t, ok, tt.wantBool)
+		})
+	}
+}