diff --git a/index.js b/index.js
index 5958c934..d2b8b725 100644
--- a/index.js
+++ b/index.js
@@ -680,7 +680,15 @@ function buildArrayTypeCondition (type, accessor) {
       condition = `obj${accessor} === null`
       break
     case 'string':
-      condition = `typeof obj${accessor} === 'string'`
+      condition = `typeof obj${accessor} === 'string' ||
+      obj${accessor} === null ||
+      obj${accessor} instanceof Date ||
+      obj${accessor} instanceof RegExp ||
+      (
+        typeof obj${accessor} === "object" &&
+        typeof obj${accessor}.toString === "function" &&
+        obj${accessor}.toString !== Object.prototype.toString
+      )`
       break
     case 'integer':
       condition = `Number.isInteger(obj${accessor})`
@@ -740,8 +748,7 @@ function buildMultiTypeSerializer (context, location, input) {
             (
               typeof ${input} === "object" &&
               typeof ${input}.toString === "function" &&
-              ${input}.toString !== Object.prototype.toString &&
-              !(${input} instanceof Date)
+              ${input}.toString !== Object.prototype.toString
             )
           )
             ${nestedResult}
diff --git a/test/array.test.js b/test/array.test.js
index 6aa2f83a..fbffe02f 100644
--- a/test/array.test.js
+++ b/test/array.test.js
@@ -31,12 +31,36 @@ function buildTest (schema, toStringify, options) {
     const stringify = build(schema, options)
     const output = stringify(toStringify)
 
-    t.same(JSON.parse(output), toStringify)
+    t.same(JSON.parse(output), JSON.parse(JSON.stringify(toStringify)))
     t.equal(output, JSON.stringify(toStringify))
     t.ok(validate(JSON.parse(output)), 'valid schema')
   })
 }
 
+buildTest({
+  title: 'dates tuple',
+  type: 'object',
+  properties: {
+    dates: {
+      type: 'array',
+      minItems: 2,
+      maxItems: 2,
+      items: [
+        {
+          type: 'string',
+          format: 'date-time'
+        },
+        {
+          type: 'string',
+          format: 'date-time'
+        }
+      ]
+    }
+  }
+}, {
+  dates: [new Date(1), new Date(2)]
+})
+
 buildTest({
   title: 'string array',
   type: 'object',