diff --git a/dist/functions/address.js b/dist/functions/address.js
index 9c287f6..2dbb56a 100644
--- a/dist/functions/address.js
+++ b/dist/functions/address.js
@@ -183,6 +183,7 @@ module.exports = function (S) {
       return checksum.equals(verifyChecksum);
     } else {
       var prefix, payload;
+      if (address !== address.toLowerCase() && address !== address.toUpperCase()) return false;
 
       if ([S.TESTNET_SEGWIT_ADDRESS_PREFIX, S.MAINNET_SEGWIT_ADDRESS_PREFIX].includes(address.split("1")[0].toLowerCase())) {
         if (address.length !== 43 && address.length !== 63 && address.length !== 44 && address.length !== 64) return false;
diff --git a/src/functions/address.js b/src/functions/address.js
index b23391b..ded0e5c 100644
--- a/src/functions/address.js
+++ b/src/functions/address.js
@@ -205,6 +205,7 @@ module.exports = function (S) {
 
         } else {
             let prefix, payload;
+            if (address !== address.toLowerCase() && address !== address.toUpperCase()) return false;
             if ([S.TESTNET_SEGWIT_ADDRESS_PREFIX,
                 S.MAINNET_SEGWIT_ADDRESS_PREFIX].includes(address.split("1")[0].toLowerCase())) {
                 if (address.length !== 43 && address.length !== 63 && address.length !== 44 && address.length !== 64) return false;
diff --git a/test/jsbgl.test.js b/test/jsbgl.test.js
index 30834cc..41dfa08 100644
--- a/test/jsbgl.test.js
+++ b/test/jsbgl.test.js
@@ -842,7 +842,11 @@ describe(`${(browser) ? 'Browser' : 'Node'} test jsbgl library`, function () {
 
         it('isAddressValid', () => {
             equal(isAddressValid("bgl1qw508d6qejxtdg4y5r3zarvary0c5xw7k0fy5a3"), true);
+            equal(isAddressValid("BGL1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7K0FY5A3"), true);
+            equal(isAddressValid("Bgl1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7K0FY5A3"), false);
             equal(isAddressValid("tbgl1qw508d6qejxtdg4y5r3zarvary0c5xw7kxpjzsx", {testnet: true}), true);
+            equal(isAddressValid("TBGL1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KXPJZSX", {testnet: true}), true);
+            equal(isAddressValid("Tbgl1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KXPJZSX", {testnet: true}), false);
             equal(isAddressValid("tbgl1qw508d6qejxtdg4y5r3zarvary0c5xw7kxpjzsx"), false);
             // equal(isAddressValid("bc1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3qccfmv3"), true);
             // equal(isAddressValid("tb1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3q0sl5k7", {testnet: true}), true);