diff --git a/src/lib/isBIC.js b/src/lib/isBIC.js
index 1420da69a..240bfe18b 100644
--- a/src/lib/isBIC.js
+++ b/src/lib/isBIC.js
@@ -1,8 +1,17 @@
 import assertString from './util/assertString';
+import { CountryCodes } from './isISO31661Alpha2';
 
-const isBICReg = /^[A-z]{4}[A-z]{2}\w{2}(\w{3})?$/;
+// https://en.wikipedia.org/wiki/ISO_9362
+const isBICReg = /^[A-Za-z]{6}[A-Za-z0-9]{2}([A-Za-z0-9]{3})?$/;
 
 export default function isBIC(str) {
   assertString(str);
+
+  // toUpperCase() should be removed when a new major version goes out that changes
+  // the regex to [A-Z] (per the spec).
+  if (CountryCodes.indexOf(str.slice(4, 6).toUpperCase()) < 0) {
+    return false;
+  }
+
   return isBICReg.test(str);
 }
diff --git a/src/lib/isISO31661Alpha2.js b/src/lib/isISO31661Alpha2.js
index ee1c33a40..e91ae8717 100644
--- a/src/lib/isISO31661Alpha2.js
+++ b/src/lib/isISO31661Alpha2.js
@@ -1,5 +1,4 @@
 import assertString from './util/assertString';
-import includes from './util/includes';
 
 // from https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
 const validISO31661Alpha2CountriesCodes = [
@@ -32,5 +31,7 @@ const validISO31661Alpha2CountriesCodes = [
 
 export default function isISO31661Alpha2(str) {
   assertString(str);
-  return includes(validISO31661Alpha2CountriesCodes, str.toUpperCase());
+  return validISO31661Alpha2CountriesCodes.indexOf(str.toUpperCase()) >= 0;
 }
+
+export const CountryCodes = validISO31661Alpha2CountriesCodes;
diff --git a/src/lib/isLocale.js b/src/lib/isLocale.js
index ab66e5c59..cacac8aec 100644
--- a/src/lib/isLocale.js
+++ b/src/lib/isLocale.js
@@ -1,6 +1,6 @@
 import assertString from './util/assertString';
 
-const localeReg = /^[A-z]{2,4}([_-]([A-z]{4}|[\d]{3}))?([_-]([A-z]{2}|[\d]{3}))?$/;
+const localeReg = /^[A-Za-z]{2,4}([_-]([A-Za-z]{4}|[\d]{3}))?([_-]([A-Za-z]{2}|[\d]{3}))?$/;
 
 export default function isLocale(str) {
   assertString(str);
diff --git a/src/lib/isPostalCode.js b/src/lib/isPostalCode.js
index 23b373497..6791db235 100644
--- a/src/lib/isPostalCode.js
+++ b/src/lib/isPostalCode.js
@@ -33,7 +33,7 @@ const patterns = {
   HT: /^HT\d{4}$/,
   HU: fourDigit,
   ID: fiveDigit,
-  IE: /^(?!.*(?:o))[A-z]\d[\dw]\s\w{4}$/i,
+  IE: /^(?!.*(?:o))[A-Za-z]\d[\dw]\s\w{4}$/i,
   IL: /^(\d{5}|\d{7})$/,
   IN: /^((?!10|29|35|54|55|65|66|86|87|88|89)[1-9][0-9]{5})$/,
   IR: /\b(?!(\d)\1{3})[13-9]{4}[1346-9][013-9]{5}\b/,