diff --git a/src/lib/isBoolean.js b/src/lib/isBoolean.js
index 9fddc2b48..40ebd3504 100644
--- a/src/lib/isBoolean.js
+++ b/src/lib/isBoolean.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesArray';
 
 const defaultOptions = { loose: false };
 const strictBooleans = ['true', 'false', '1', '0'];
@@ -8,8 +9,8 @@ export default function isBoolean(str, options = defaultOptions) {
   assertString(str);
 
   if (options.loose) {
-    return looseBooleans.includes(str.toLowerCase());
+    return includes(looseBooleans, str.toLowerCase());
   }
 
-  return strictBooleans.includes(str);
+  return includes(strictBooleans, str);
 }
diff --git a/src/lib/isDecimal.js b/src/lib/isDecimal.js
index 488668a52..474eff2b0 100644
--- a/src/lib/isDecimal.js
+++ b/src/lib/isDecimal.js
@@ -1,6 +1,6 @@
 import merge from './util/merge';
 import assertString from './util/assertString';
-import includes from './util/includes';
+import includes from './util/includesArray';
 import { decimal } from './alpha';
 
 function decimalRegExp(options) {
diff --git a/src/lib/isEmail.js b/src/lib/isEmail.js
index 6db00195c..0d16c24a9 100644
--- a/src/lib/isEmail.js
+++ b/src/lib/isEmail.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesArray';
 
 import merge from './util/merge';
 import isByteLength from './isByteLength';
@@ -96,11 +97,11 @@ export default function isEmail(str, options) {
   const domain = parts.pop();
   const lower_domain = domain.toLowerCase();
 
-  if (options.host_blacklist.includes(lower_domain)) {
+  if (includes(options.host_blacklist, lower_domain)) {
     return false;
   }
 
-  if (options.host_whitelist.length > 0 && !options.host_whitelist.includes(lower_domain)) {
+  if (options.host_whitelist.length > 0 && !includes(options.host_whitelist, lower_domain)) {
     return false;
   }
 
diff --git a/src/lib/isIdentityCard.js b/src/lib/isIdentityCard.js
index d34ddae26..34d60cebf 100644
--- a/src/lib/isIdentityCard.js
+++ b/src/lib/isIdentityCard.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesArray';
 import isInt from './isInt';
 
 const validators = {
@@ -277,7 +278,7 @@ const validators = {
 
     const parityBit = ['1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2'];
 
-    const checkAddressCode = addressCode => provincesAndCities.includes(addressCode);
+    const checkAddressCode = addressCode => includes(provincesAndCities, addressCode);
 
     const checkBirthDayCode = (birDayCode) => {
       const yyyy = parseInt(birDayCode.substring(0, 4), 10);
diff --git a/src/lib/isJSON.js b/src/lib/isJSON.js
index d3731e337..5c51dd31c 100644
--- a/src/lib/isJSON.js
+++ b/src/lib/isJSON.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesArray';
 import merge from './util/merge';
 
 const default_json_options = {
@@ -15,7 +16,7 @@ export default function isJSON(str, options) {
     }
 
     const obj = JSON.parse(str);
-    return primitives.includes(obj) || (!!obj && typeof obj === 'object');
+    return includes(primitives, obj) || (!!obj && typeof obj === 'object');
   } catch (e) { /* ignore */ }
   return false;
 }
diff --git a/src/lib/isLatLong.js b/src/lib/isLatLong.js
index 5c53c23aa..bdc9f7272 100644
--- a/src/lib/isLatLong.js
+++ b/src/lib/isLatLong.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesString';
 import merge from './util/merge';
 
 const lat = /^\(?[+-]?(90(\.0+)?|[1-8]?\d(\.\d+)?)$/;
@@ -15,7 +16,7 @@ export default function isLatLong(str, options) {
   assertString(str);
   options = merge(options, defaultLatLongOptions);
 
-  if (!str.includes(',')) return false;
+  if (!includes(str, ',')) return false;
   const pair = str.split(',');
   if ((pair[0].startsWith('(') && !pair[1].endsWith(')'))
     || (pair[1].endsWith(')') && !pair[0].startsWith('('))) return false;
diff --git a/src/lib/isURL.js b/src/lib/isURL.js
index 3d2b1df3e..00efa9ec5 100644
--- a/src/lib/isURL.js
+++ b/src/lib/isURL.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesString';
 
 import isFQDN from './isFQDN';
 import isIP from './isIP';
@@ -63,11 +64,11 @@ export default function isURL(url, options) {
     return false;
   }
 
-  if (!options.allow_fragments && url.includes('#')) {
+  if (!options.allow_fragments && includes(url, '#')) {
     return false;
   }
 
-  if (!options.allow_query_components && (url.includes('?') || url.includes('&'))) {
+  if (!options.allow_query_components && (includes(url, '?') || includes(url, '&'))) {
     return false;
   }
 
diff --git a/src/lib/isUUID.js b/src/lib/isUUID.js
index c026ca78c..da6a4de44 100644
--- a/src/lib/isUUID.js
+++ b/src/lib/isUUID.js
@@ -1,4 +1,5 @@
 import assertString from './util/assertString';
+import includes from './util/includesArray';
 
 const uuid = {
   1: /^[0-9A-F]{8}-[0-9A-F]{4}-1[0-9A-F]{3}-[0-9A-F]{4}-[0-9A-F]{12}$/i,
@@ -11,6 +12,6 @@ const uuid = {
 
 export default function isUUID(str, version) {
   assertString(str);
-  const pattern = uuid[![undefined, null].includes(version) ? version : 'all'];
+  const pattern = uuid[!includes([undefined, null], version) ? version : 'all'];
   return !!pattern && pattern.test(str);
 }
diff --git a/src/lib/util/includes.js b/src/lib/util/includesArray.js
similarity index 100%
rename from src/lib/util/includes.js
rename to src/lib/util/includesArray.js
diff --git a/src/lib/util/includesString.js b/src/lib/util/includesString.js
new file mode 100644
index 000000000..41a50bba8
--- /dev/null
+++ b/src/lib/util/includesString.js
@@ -0,0 +1,3 @@
+const includes = (str, val) => str.indexOf(val) !== -1;
+
+export default includes;