diff --git a/src/api/common/schema-validator.js b/src/api/common/schema-validator.js
index 56d2fb70..e4626634 100644
--- a/src/api/common/schema-validator.js
+++ b/src/api/common/schema-validator.js
@@ -12,7 +12,9 @@ const ValidationError = require('./errors').ValidationError;
 let SCHEMAS = {};
 
 function isValidAddress(address: string): boolean {
-  return core.UInt160.is_valid(address);
+  return typeof address === 'string' && address.length > 0 &&
+    address[0] === 'r' &&
+    core.UInt160.is_valid(address);
 }
 
 function isValidLedgerHash(ledgerHash) {
diff --git a/test/api-test.js b/test/api-test.js
index 9f3afc3b..3987a3ba 100644
--- a/test/api-test.js
+++ b/test/api-test.js
@@ -803,4 +803,11 @@ describe('RippleAPI - offline', function() {
     const api = new RippleAPI();
     assert(!api.isValidAddress(address.slice(0, -1) + 'a'));
   });
+
+  it('isValidAddress - invalid - hex representation', function() {
+    const api = new RippleAPI();
+    const hex = '6e3efa86a5eb0a3c5dc9beb3a204783bb00e1913';
+    assert(!api.isValidAddress(hex));
+  });
+
 });