diff --git a/src/module/module-collection.js b/src/module/module-collection.js
index 095872882..75e641fce 100644
--- a/src/module/module-collection.js
+++ b/src/module/module-collection.js
@@ -72,7 +72,11 @@ export default class ModuleCollection {
     const parent = this.get(path.slice(0, -1))
     const key = path[path.length - 1]
 
-    return parent.hasChild(key)
+    if (parent) {
+      return parent.hasChild(key)
+    }
+
+    return false
   }
 }
 
diff --git a/test/unit/module/module-collection.spec.js b/test/unit/module/module-collection.spec.js
index 3e8081ce3..514965cab 100644
--- a/test/unit/module/module-collection.spec.js
+++ b/test/unit/module/module-collection.spec.js
@@ -81,6 +81,23 @@ describe('ModuleCollection', () => {
     expect(collection.get(['a'])).toBe(undefined)
   })
 
+  it('isRegistered', () => {
+    const collection = new ModuleCollection({})
+
+    collection.register(['a'], {
+      state: { value: true }
+    })
+
+    collection.register(['a', 'b'], {
+      state: { value: false }
+    })
+
+    expect(collection.isRegistered(['a'])).toBe(true)
+    expect(collection.isRegistered(['a', 'b'])).toBe(true)
+    expect(collection.isRegistered(['c'])).toBe(false)
+    expect(collection.isRegistered(['c', 'd'])).toBe(false)
+  })
+
   it('does not unregister initial modules', () => {
     const collection = new ModuleCollection({
       modules: {
diff --git a/test/unit/modules.spec.js b/test/unit/modules.spec.js
index 0fb113784..17a09857b 100644
--- a/test/unit/modules.spec.js
+++ b/test/unit/modules.spec.js
@@ -91,6 +91,18 @@ describe('Modules', () => {
       expect(store.hasModule('bonjour')).toBe(false)
     })
 
+    it('dynamic module existance test with nested modules', () => {
+      const store = new Vuex.Store({})
+
+      store.registerModule('a', {})
+      store.registerModule(['a', 'b'], {})
+
+      expect(store.hasModule(['a'])).toBe(true)
+      expect(store.hasModule(['a', 'b'])).toBe(true)
+      expect(store.hasModule(['c'])).toBe(false)
+      expect(store.hasModule(['c', 'd'])).toBe(false)
+    })
+
     it('dynamic module registration preserving hydration', () => {
       const store = new Vuex.Store({})
       store.replaceState({ a: { foo: 'state' }})