diff --git a/types/lodash/ts3.1/common/array.d.ts b/types/lodash/ts3.1/common/array.d.ts
index 73e4e642c2..3831ba97ce 100644
--- a/types/lodash/ts3.1/common/array.d.ts
+++ b/types/lodash/ts3.1/common/array.d.ts
@@ -488,7 +488,9 @@ declare module "../index" {
          */
         flatten(): T extends Many<infer U> ? CollectionChain<U> : CollectionChain<T>;
     }
-    type Flat<T> = (T extends List<any> ? never : T);
+
+    type Flat<T> = T extends string ? T : (T extends List<any> ? never : T);
+
     interface LoDashStatic {
         /**
          * Recursively flattens a nested array.
diff --git a/types/lodash/ts3.1/lodash-tests.ts b/types/lodash/ts3.1/lodash-tests.ts
index 339f1f2c3e..927a8fae8c 100644
--- a/types/lodash/ts3.1/lodash-tests.ts
+++ b/types/lodash/ts3.1/lodash-tests.ts
@@ -497,6 +497,9 @@ _.chain([1, 2, 3, 4]).unshift(5, 6); // $ExpectType CollectionChain<number>
     _.flattenDeep([1, [2, [3, [4, 5]]]]); // $ExpectType number[]
     _.flattenDeep({0: 1, 1: [2, [3, [4, 5]]], length: 2}); // $ExpectType number[]
 
+    _.flattenDeep(['x']); // $ExpectType string[]
+    _.flattenDeep(['x', ['y']]); // $ExpectType string[]
+
     _.flattenDeep<number>([1, 2, 3]); // $ExpectType number[]
     _.flattenDeep<number>([[1, 2, 3]]); // $ExpectType number[]
     _.flattenDeep<number>([1, [2, [3, [4, 5]]]]); // $ExpectType number[]