diff --git a/lib/rules/no-unused-prop-types.js b/lib/rules/no-unused-prop-types.js
index f595ce58ee..3b3b4093c5 100644
--- a/lib/rules/no-unused-prop-types.js
+++ b/lib/rules/no-unused-prop-types.js
@@ -258,6 +258,14 @@ module.exports = {
       return tokens.length && tokens[0].value === '...';
     }
 
+    /**
+     * Removes quotes from around an identifier.
+     * @param {string} the identifier to strip
+     */
+    function stripQuotes(string) {
+      return string.replace(/^\'|\'$/g, '');
+    }
+
     /**
      * Retrieve the name of a key node
      * @param {ASTNode} node The AST node with the key.
@@ -265,8 +273,11 @@ module.exports = {
      */
     function getKeyValue(node) {
       if (node.type === 'ObjectTypeProperty') {
-        const tokens = context.getFirstTokens(node, 1);
-        return tokens[0].value;
+        const tokens = context.getFirstTokens(node, 2);
+        return (tokens[0].value === '+' || tokens[0].value === '-'
+          ? tokens[1].value
+          : stripQuotes(tokens[0].value)
+        );
       }
       const key = node.key || node.argument;
       return key.type === 'Identifier' ? key.name : key.value;
diff --git a/lib/rules/prop-types.js b/lib/rules/prop-types.js
index 6e7f48dfc8..5276474058 100644
--- a/lib/rules/prop-types.js
+++ b/lib/rules/prop-types.js
@@ -333,10 +333,7 @@ module.exports = {
      * @param {string} the identifier to strip
      */
     function stripQuotes(string) {
-      if (string[0] === '\'' || string[0] === '"' && string[0] === string[string.length - 1]) {
-        return string.slice(1, string.length - 1);
-      }
-      return string;
+      return string.replace(/^\'|\'$/g, '');
     }
 
     /**
diff --git a/tests/lib/rules/no-unused-prop-types.js b/tests/lib/rules/no-unused-prop-types.js
index 2a8b4557b8..783cac6f79 100644
--- a/tests/lib/rules/no-unused-prop-types.js
+++ b/tests/lib/rules/no-unused-prop-types.js
@@ -2032,27 +2032,50 @@ ruleTester.run('no-unused-prop-types', rule, {
     }, {
       // issue #106
       code: `
-      import React from 'react';
-      import SharedPropTypes from './SharedPropTypes';
+        import React from 'react';
+        import SharedPropTypes from './SharedPropTypes';
 
-      export default class A extends React.Component {
-        render() {
-          return (
-            <span
-              a={this.props.a}
-              b={this.props.b}
-              c={this.props.c}>
-              {this.props.children}
-            </span>
-          );
+        export default class A extends React.Component {
+          render() {
+            return (
+              <span
+                a={this.props.a}
+                b={this.props.b}
+                c={this.props.c}>
+                {this.props.children}
+              </span>
+            );
+          }
         }
-      }
 
-      A.propTypes = {
-        a: React.PropTypes.string,
-        ...SharedPropTypes // eslint-disable-line object-shorthand
-      };
-    `,
+        A.propTypes = {
+          a: React.PropTypes.string,
+          ...SharedPropTypes // eslint-disable-line object-shorthand
+        };
+      `,
+      parser: 'babel-eslint'
+    }, {
+      // issue #933
+      code: `
+        type Props = {
+          +foo: number
+        }
+        class MyComponent extends React.Component {
+          render() {
+            return <div>{this.props.foo}</div>
+          }
+        }
+      `,
+      parser: 'babel-eslint'
+    }, {
+      code: `
+        type Props = {
+          \'completed?\': boolean,
+        };
+        const Hello = (props: Props): React.Element => {
+          return <div>{props[\'completed?\']}</div>;
+        }
+      `,
       parser: 'babel-eslint'
     }
   ],