diff --git a/src/class/OptionRegistry.js b/src/class/OptionRegistry.js
index 7ed7c203a8e232be28f087b4dc7e58c7d2746714..830e9584c78e04e1a6f4a15dc838a002cbe85ca9 100644
--- a/src/class/OptionRegistry.js
+++ b/src/class/OptionRegistry.js
@@ -34,12 +34,12 @@ defaults.random = Math.random;
 class OptionRegistry extends Registry {
   constructor() {
     super();
-    this.data = Object.assign({}, defaults);
+    this.data = { ...defaults };
     this._defaults = defaults;
   }
 
   get defaults() {
-    return Object.assign({}, this._defaults);
+    return { ...this._defaults };
   }
 }
 
diff --git a/src/types/integer.js b/src/types/integer.js
index 3857b6ca06714977d6d3fbb01e8fd05078e5bcfd..4804db2c41b6b7958d8b2ca92b813cefabd27cd0 100644
--- a/src/types/integer.js
+++ b/src/types/integer.js
@@ -5,7 +5,7 @@ import number from './number';
 // part, leaving the result as an integer.
 
 function integerType(value) {
-  return number(Object.assign({ multipleOf: 1 }, value));
+  return number({ multipleOf: 1, ...value });
 }
 
 export default integerType;
diff --git a/tests/schema/helpers.js b/tests/schema/helpers.js
index 9e9bfdf767d034672bb6a095c07edc51b060dd7a..8573eb6de54fb8ac813bb15f4a74c067d60a89eb 100644
--- a/tests/schema/helpers.js
+++ b/tests/schema/helpers.js
@@ -38,7 +38,7 @@ export function getTests(srcDir) {
 
       let _only = false;
 
-      suite = Object.assign({ file }, x);
+      suite = { file, ...x };
 
       suite.tests = suite.tests.sort((a, b) => {
         if (a.only) return -1;