diff --git a/index.d.ts b/index.d.ts
index 13396202..c31b6fd5 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -629,7 +629,7 @@ declare namespace mercurius {
     /**
      *  Return the query for a given hash.
      */
-    getQueryFromHash: (hash: string) => Promise<string>;
+    getQueryFromHash: (hash: string) => Promise<string | undefined>;
     /**
      *  Return the hash for a given query string. Do not provide if you want to skip saving new queries.
      */
diff --git a/test/types/index.ts b/test/types/index.ts
index 4e863989..39e4b8b6 100644
--- a/test/types/index.ts
+++ b/test/types/index.ts
@@ -654,3 +654,36 @@ expectType<typeof mercurius.ErrorWithProps>(ErrorWithProps)
 expectType<typeof mercurius.defaultErrorFormatter>(defaultErrorFormatter)
 expectType<typeof mercurius.persistedQueryDefaults>(persistedQueryDefaults)
 expectType<typeof mercurius.withFilter>(withFilter)
+
+app.register(mercurius, {
+  schema,
+  resolvers,
+  persistedQueryProvider: {
+    ...persistedQueryDefaults.automatic(),
+    getQueryFromHash: () => {
+      return Promise.resolve('foo')
+    },
+  }
+})
+
+app.register(mercurius, {
+  schema,
+  resolvers,
+  persistedQueryProvider: {
+    ...persistedQueryDefaults.automatic(),
+    getQueryFromHash: () => {
+      return Promise.resolve(undefined)
+    },
+  }
+})
+
+expectError(app.register(mercurius, {
+  schema,
+  resolvers,
+  persistedQueryProvider: {
+    ...persistedQueryDefaults.automatic(),
+    getQueryFromHash: () => {
+      return Promise.resolve(false)
+    },
+  }
+}))