diff --git a/hyperglass/ui/components/looking-glass-form.tsx b/hyperglass/ui/components/looking-glass-form.tsx
index 5a095ddd..87693fa9 100644
--- a/hyperglass/ui/components/looking-glass-form.tsx
+++ b/hyperglass/ui/components/looking-glass-form.tsx
@@ -15,22 +15,11 @@ import {
 import { useConfig } from '~/context';
 import { FormRow } from '~/elements';
 import { useStrf, useGreeting, useDevice, useFormState } from '~/hooks';
+import { isFQDN } from '~/util';
 import { isString, isQueryField, Directive } from '~/types';
 
 import type { FormData, OnChangeArgs } from '~/types';
 
-/**
- * Don't set the global flag on this.
- * @see https://stackoverflow.com/questions/24084926/javascript-regexp-cant-use-twice
- *
- * TLDR: the test() will pass the first time, but not the second. In React Strict Mode & in a dev
- * environment, this will mean isFqdn will be true the first time, then false the second time,
- * submitting the FQDN to hyperglass the second time.
- */
-const fqdnPattern = new RegExp(
-  /^(?!:\/\/)([a-zA-Z0-9-]+\.)?[a-zA-Z0-9-][a-zA-Z0-9-]+\.[a-zA-Z-]{2,6}?$/im,
-);
-
 export const LookingGlassForm = (): JSX.Element => {
   const { web, messages } = useConfig();
 
@@ -84,7 +73,7 @@ export const LookingGlassForm = (): JSX.Element => {
   // const isFqdnQuery = useIsFqdn(form.queryTarget, form.queryType);
   const isFqdnQuery = useCallback(
     (target: string, fieldType: Directive['fieldType'] | null): boolean =>
-      fieldType === 'text' && fqdnPattern.test(target),
+      fieldType === 'text' && isFQDN(target),
     [],
   );
 
diff --git a/hyperglass/ui/util/common.test.ts b/hyperglass/ui/util/common.test.ts
index 55f9f77b..80eef5bc 100644
--- a/hyperglass/ui/util/common.test.ts
+++ b/hyperglass/ui/util/common.test.ts
@@ -1,4 +1,4 @@
-import { all, chunkArray, entries, dedupObjectArray, andJoin } from './common';
+import { all, chunkArray, entries, dedupObjectArray, andJoin, isFQDN } from './common';
 
 test('all - all items are truthy', () => {
   expect(all(1 === 1, true, 'one' === 'one')).toBe(true);
@@ -74,3 +74,27 @@ describe('andJoin - join array of strings to sentence structure', () => {
     expect(result).toBe('Tom, Dick & Harry');
   });
 });
+
+describe('isFQDN - determine if a string is an FQDN pattern', () => {
+  it('is null and should be false', () => {
+    expect(isFQDN(null)).toBe(false);
+  });
+  it('is undefined and should be false', () => {
+    expect(isFQDN(undefined)).toBe(false);
+  });
+  it("isn't an FQDN and should be false", () => {
+    expect(isFQDN('example')).toBe(false);
+  });
+  it('is a domain and should be true', () => {
+    expect(isFQDN('example.com')).toBe(true);
+  });
+  it('is a simple FQDN and should be true', () => {
+    expect(isFQDN('www.example.com')).toBe(true);
+  });
+  it('is a long FQDN and should be true', () => {
+    expect(isFQDN('one.two.example.com')).toBe(true);
+  });
+  it('is a longer FQDN and should be true', () => {
+    expect(isFQDN('one.two.three.four.five.example.com')).toBe(true);
+  });
+});
diff --git a/hyperglass/ui/util/common.ts b/hyperglass/ui/util/common.ts
index 4650874e..67eedc19 100644
--- a/hyperglass/ui/util/common.ts
+++ b/hyperglass/ui/util/common.ts
@@ -124,3 +124,23 @@ export function andJoin(values: string[], options?: AndJoinOptions): string {
   }
   return last;
 }
+
+/**
+ * Determine if an input value is an FQDN string.
+ *
+ * @param value Input value.
+ */
+export function isFQDN(value: unknown): value is string {
+  /**
+   * Don't set the global flag on this.
+   * @see https://stackoverflow.com/questions/24084926/javascript-regexp-cant-use-twice
+   *
+   * TLDR: the test() will pass the first time, but not the second. In React Strict Mode & in a dev
+   * environment, this will mean isFqdn will be true the first time, then false the second time,
+   * submitting the FQDN to hyperglass the second time.
+   */
+  const pattern = new RegExp(
+    /^(?!:\/\/)([a-zA-Z0-9-]+\.)*[a-zA-Z0-9-][a-zA-Z0-9-]+\.[a-zA-Z-]{2,6}?$/im,
+  );
+  return typeof value === 'string' && pattern.test(value);
+}