diff --git a/fakejson.test.js b/fakejson.test.js
index 0f64bae..be48594 100644
--- a/fakejson.test.js
+++ b/fakejson.test.js
@@ -33,3 +33,17 @@ test('match kind', () => {
     )
   ).toBeTruthy()
 })
+
+test('match subscription id', () => {
+  expect(fj.getSubscriptionId('["EVENT","",{}]')).toEqual('')
+  expect(fj.getSubscriptionId('["EVENT","_",{}]')).toEqual('_')
+  expect(fj.getSubscriptionId('["EVENT","subname",{}]')).toEqual('subname')
+  expect(fj.getSubscriptionId('["EVENT", "kasjbdjkav", {}]')).toEqual(
+    'kasjbdjkav'
+  )
+  expect(
+    fj.getSubscriptionId(
+      '  [ \n\n "EVENT"  , \n\n "y4d5ow45gfwoiudfÇA VSADLKAN KLDASB[12312535]SFMZSNJKLH" , {}]'
+    )
+  ).toEqual('y4d5ow45gfwoiudfÇA VSADLKAN KLDASB[12312535]SFMZSNJKLH')
+})
diff --git a/fakejson.ts b/fakejson.ts
index 3ba5fc0..0eda78c 100644
--- a/fakejson.ts
+++ b/fakejson.ts
@@ -13,6 +13,21 @@ export function getInt(json: string, field: string): number {
   return parseInt(sliced.slice(0, end), 10)
 }
 
+export function getSubscriptionId(json: string): string | null {
+  let idx = json.slice(0, 22).indexOf(`"EVENT"`)
+  if (idx === -1) return null
+
+  let pstart = json.slice(idx + 7 + 1).indexOf(`"`)
+  if (pstart === -1) return null
+  let start = idx + 7 + 1 + pstart
+
+  let pend = json.slice(start + 1, 80).indexOf(`"`)
+  if (pend === -1) return null
+  let end = start + 1 + pend
+
+  return json.slice(start + 1, end)
+}
+
 export function matchEventId(json: string, id: string): boolean {
   return id === getHex64(json, 'id')
 }