diff --git a/src/utils/filter.ts b/src/utils/filter.ts
index 916e5013..2e1d5c94 100644
--- a/src/utils/filter.ts
+++ b/src/utils/filter.ts
@@ -1 +1 @@
-export const isGenericTagQuery = (key: string) => /^#[a-z]$/.test(key)
+export const isGenericTagQuery = (key: string) => /^#[a-zA-Z]$/.test(key)
diff --git a/test/unit/utils/filter.ts b/test/unit/utils/filter.ts
new file mode 100644
index 00000000..775dd426
--- /dev/null
+++ b/test/unit/utils/filter.ts
@@ -0,0 +1,21 @@
+import { expect } from 'chai'
+
+import { isGenericTagQuery } from '../../../src/utils/filter'
+
+describe('isGenericTagQuery', () => {
+  it('returns true for #a', () => {
+    expect(isGenericTagQuery('#a')).to.be.true
+  })
+
+  it('returns true for #A', () => {
+    expect(isGenericTagQuery('#A')).to.be.true
+  })
+
+  it('returns false for #0', () => {
+    expect(isGenericTagQuery('#0')).to.be.false
+  })
+
+  it('returns false for #abc', () => {
+    expect(isGenericTagQuery('#abc')).to.be.false
+  })
+})