diff --git a/policy/options_117_test.go b/policy/options_117_test.go
new file mode 100644
index 00000000..bd3d287d
--- /dev/null
+++ b/policy/options_117_test.go
@@ -0,0 +1,119 @@
+//go:build !go1.18
+// +build !go1.18
+
+package policy
+
+import "testing"
+
+func Test_normalizeAndValidateURIDomainConstraint(t *testing.T) {
+	tests := []struct {
+		name       string
+		constraint string
+		want       string
+		wantErr    bool
+	}{
+		{
+			name:       "fail/empty-constraint",
+			constraint: "",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/scheme-https",
+			constraint: `https://*.local`,
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/too-many-asterisks",
+			constraint: "**.local",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/empty-label",
+			constraint: "..local",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/empty-reverse",
+			constraint: ".",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/domain-with-port",
+			constraint: "host.local:8443",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv4",
+			constraint: "127.0.0.1",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv6-brackets",
+			constraint: "[::1]",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv6-no-brackets",
+			constraint: "::1",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv6-no-brackets",
+			constraint: "[::1",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/idna-internationalized-domain-name-lookup",
+			constraint: `\00local`,
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "ok/wildcard",
+			constraint: "*.local",
+			want:       ".local",
+			wantErr:    false,
+		},
+		{
+			name:       "ok/specific-domain",
+			constraint: "example.local",
+			want:       "example.local",
+			wantErr:    false,
+		},
+		{
+			name:       "ok/idna-internationalized-domain-name-lookup",
+			constraint: `*.bücher.example.com`,
+			want:       ".xn--bcher-kva.example.com",
+			wantErr:    false,
+		},
+		{
+			// IDNA2003 vs. 2008 deviation: https://unicode.org/reports/tr46/#Deviations results
+			// in a difference between Go 1.18 and lower versions. Go 1.18 expects ".xn--fa-hia.de"; not .fass.de.
+			name:       "ok/idna-internationalized-domain-name-lookup-deviation",
+			constraint: `*.faß.de`,
+			want:       ".fass.de",
+			wantErr:    false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := normalizeAndValidateURIDomainConstraint(tt.constraint)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("normalizeAndValidateURIDomainConstraint() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			if got != tt.want {
+				t.Errorf("normalizeAndValidateURIDomainConstraint() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/policy/options_118_test.go b/policy/options_118_test.go
new file mode 100644
index 00000000..059f1177
--- /dev/null
+++ b/policy/options_118_test.go
@@ -0,0 +1,119 @@
+//go:build go1.18
+// +build go1.18
+
+package policy
+
+import "testing"
+
+func Test_normalizeAndValidateURIDomainConstraint(t *testing.T) {
+	tests := []struct {
+		name       string
+		constraint string
+		want       string
+		wantErr    bool
+	}{
+		{
+			name:       "fail/empty-constraint",
+			constraint: "",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/scheme-https",
+			constraint: `https://*.local`,
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/too-many-asterisks",
+			constraint: "**.local",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/empty-label",
+			constraint: "..local",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/empty-reverse",
+			constraint: ".",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/domain-with-port",
+			constraint: "host.local:8443",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv4",
+			constraint: "127.0.0.1",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv6-brackets",
+			constraint: "[::1]",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv6-no-brackets",
+			constraint: "::1",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/ipv6-no-brackets",
+			constraint: "[::1",
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "fail/idna-internationalized-domain-name-lookup",
+			constraint: `\00local`,
+			want:       "",
+			wantErr:    true,
+		},
+		{
+			name:       "ok/wildcard",
+			constraint: "*.local",
+			want:       ".local",
+			wantErr:    false,
+		},
+		{
+			name:       "ok/specific-domain",
+			constraint: "example.local",
+			want:       "example.local",
+			wantErr:    false,
+		},
+		{
+			name:       "ok/idna-internationalized-domain-name-lookup",
+			constraint: `*.bücher.example.com`,
+			want:       ".xn--bcher-kva.example.com",
+			wantErr:    false,
+		},
+		{
+			// IDNA2003 vs. 2008 deviation: https://unicode.org/reports/tr46/#Deviations results
+			// in a difference between Go 1.18 and lower versions. Go 1.18 expects ".xn--fa-hia.de"; not .fass.de.
+			name:       "ok/idna-internationalized-domain-name-lookup-deviation",
+			constraint: `*.faß.de`,
+			want:       ".xn--fa-hia.de",
+			wantErr:    false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := normalizeAndValidateURIDomainConstraint(tt.constraint)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("normalizeAndValidateURIDomainConstraint() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			if got != tt.want {
+				t.Errorf("normalizeAndValidateURIDomainConstraint() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/policy/options_test.go b/policy/options_test.go
index 8a64f282..b7390545 100644
--- a/policy/options_test.go
+++ b/policy/options_test.go
@@ -184,117 +184,6 @@ func Test_normalizeAndValidateEmailConstraint(t *testing.T) {
 	}
 }
 
-func Test_normalizeAndValidateURIDomainConstraint(t *testing.T) {
-	tests := []struct {
-		name       string
-		constraint string
-		want       string
-		wantErr    bool
-	}{
-		{
-			name:       "fail/empty-constraint",
-			constraint: "",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/scheme-https",
-			constraint: `https://*.local`,
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/too-many-asterisks",
-			constraint: "**.local",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/empty-label",
-			constraint: "..local",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/empty-reverse",
-			constraint: ".",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/domain-with-port",
-			constraint: "host.local:8443",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/ipv4",
-			constraint: "127.0.0.1",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/ipv6-brackets",
-			constraint: "[::1]",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/ipv6-no-brackets",
-			constraint: "::1",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/ipv6-no-brackets",
-			constraint: "[::1",
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "fail/idna-internationalized-domain-name-lookup",
-			constraint: `\00local`,
-			want:       "",
-			wantErr:    true,
-		},
-		{
-			name:       "ok/wildcard",
-			constraint: "*.local",
-			want:       ".local",
-			wantErr:    false,
-		},
-		{
-			name:       "ok/specific-domain",
-			constraint: "example.local",
-			want:       "example.local",
-			wantErr:    false,
-		},
-		{
-			name:       "ok/idna-internationalized-domain-name-lookup",
-			constraint: `*.bücher.example.com`,
-			want:       ".xn--bcher-kva.example.com",
-			wantErr:    false,
-		},
-		{
-			name:       "ok/idna-internationalized-domain-name-lookup-deviation",
-			constraint: `*.faß.de`,
-			want:       ".fass.de", // IDNA2003 vs. 2008 deviation: https://unicode.org/reports/tr46/#Deviations
-			wantErr:    false,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			got, err := normalizeAndValidateURIDomainConstraint(tt.constraint)
-			if (err != nil) != tt.wantErr {
-				t.Errorf("normalizeAndValidateURIDomainConstraint() error = %v, wantErr %v", err, tt.wantErr)
-			}
-			if got != tt.want {
-				t.Errorf("normalizeAndValidateURIDomainConstraint() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}
-
 func TestNew(t *testing.T) {
 	type test struct {
 		options []NamePolicyOption