diff --git a/packages/devtools-kit/__tests__/component/format.test.ts b/packages/devtools-kit/__tests__/component/format.test.ts
index 792c3466f..1c59c8bf3 100644
--- a/packages/devtools-kit/__tests__/component/format.test.ts
+++ b/packages/devtools-kit/__tests__/component/format.test.ts
@@ -25,6 +25,17 @@ describe('format: displayText and rawValue can be calculated by formatInspectorS
     })
   })
 
+  it('type: string value "undefined" should be treated as a string, not null', () => {
+    // https://github.com/vuejs/devtools/issues/1087
+    const value = 'undefined'
+    const displayText = format.formatInspectorStateValue(value)
+    const rawValue = format.getRaw(value).value
+
+    expect(displayText).toBe('undefined')
+    expect(rawValue).toBe('undefined')
+    expect(format.getInspectorStateValueType(value)).toBe('string')
+  })
+
   it('type: plain object', () => {
     const value = { foo: 'bar' }
     const displayText = format.formatInspectorStateValue(value)
diff --git a/packages/devtools-kit/src/core/component/state/format.ts b/packages/devtools-kit/src/core/component/state/format.ts
index a6d7de1ec..b973a7142 100644
--- a/packages/devtools-kit/src/core/component/state/format.ts
+++ b/packages/devtools-kit/src/core/component/state/format.ts
@@ -6,7 +6,7 @@ import { escape, internalStateTokenToString, replaceStringToToken, replaceTokenT
 
 export function getInspectorStateValueType(value, raw = true) {
   const type = typeof value
-  if (value == null || value === UNDEFINED || value === 'undefined') {
+  if (value == null || value === UNDEFINED) {
     return 'null'
   }
   else if (