diff --git a/lib/rules/prop-types.js b/lib/rules/prop-types.js
index 7c10c71385..ed78afd07c 100644
--- a/lib/rules/prop-types.js
+++ b/lib/rules/prop-types.js
@@ -8,6 +8,7 @@
 // https://github.com/yannickcr/eslint-plugin-react/issues/7
 
 var Components = require('../util/Components');
+var variable = require('../util/variable');
 
 // ------------------------------------------------------------------------------
 // Rule Definition
@@ -518,6 +519,18 @@ module.exports = Components.detect(function(context, components, utils) {
             buildReactDeclarationTypes(propTypes.parent.right);
         }
         break;
+      case 'Identifier':
+        var variablesInScope = variable.variablesInScope(context);
+        for (var i = 0, j = variablesInScope.length; i < j; i++) {
+          if (variablesInScope[i].name !== propTypes.name) {
+            continue;
+          }
+          var defInScope = variablesInScope[i].defs[variablesInScope[i].defs.length - 1];
+          markPropTypesAsDeclared(node, defInScope.node && defInScope.node.init);
+          return;
+        }
+        ignorePropsValidation = true;
+        break;
       case null:
         break;
       default:
diff --git a/tests/lib/rules/prop-types.js b/tests/lib/rules/prop-types.js
index 746f1670fc..bb20dfe4ac 100644
--- a/tests/lib/rules/prop-types.js
+++ b/tests/lib/rules/prop-types.js
@@ -1408,6 +1408,24 @@ ruleTester.run('prop-types', rule, {
       errors: [
         {message: '\'name\' is missing in props validation'}
       ]
+    }, {
+      code: [
+        'var propTypes = {',
+        '  firstname: React.PropTypes.string',
+        '};',
+        'class Test extends React.Component {',
+        '  render() {',
+        '    return (',
+        '      <div>{this.props.firstname} {this.props.lastname}</div>',
+        '    );',
+        '  }',
+        '}',
+        'Test.propTypes = propTypes;'
+      ].join('\n'),
+      parser: 'babel-eslint',
+      errors: [
+        {message: '\'lastname\' is missing in props validation'}
+      ]
     }
   ]
 });