diff --git a/README.md b/README.md
index 5927cc2..70766f9 100644
--- a/README.md
+++ b/README.md
@@ -99,6 +99,10 @@ MyComponent.propTypes = {
   // A value of any data type
   requiredAny: PropTypes.any.isRequired,
 
+  // You can use `notNull` like `isRequired`
+  // to allow undefined but not null
+  optionalObjectNotNull: PropTypes.object.notNull,
+
   // You can also specify a custom validator. It should return an Error
   // object if the validation fails. Don't `console.warn` or throw, as this
   // won't work inside `oneOfType`.
@@ -142,7 +146,7 @@ For example:
 
 ```js
   "dependencies": {
-    "prop-types": "^15.5.7" 
+    "prop-types": "^15.5.7"
   }
 ```
 
@@ -150,10 +154,10 @@ For libraries, we *also* recommend leaving it in `dependencies`:
 
 ```js
   "dependencies": {
-    "prop-types": "^15.5.7" 
+    "prop-types": "^15.5.7"
   },
   "peerDependencies": {
-    "react": "^15.5.0" 
+    "react": "^15.5.0"
   }
 ```
 
diff --git a/__tests__/PropTypesDevelopmentStandalone-test.js b/__tests__/PropTypesDevelopmentStandalone-test.js
index 9684d56..08d662f 100644
--- a/__tests__/PropTypesDevelopmentStandalone-test.js
+++ b/__tests__/PropTypesDevelopmentStandalone-test.js
@@ -91,6 +91,27 @@ function typeCheckPass(declaration, value) {
   expect(message).toBe(null);
 }
 
+function typeCheckNullFail(declaration, value) {
+  const propTypes = {
+    testProp: declaration,
+  };
+  var mustNotBeNullMsg = 'The prop `testProp` in `testComponent`' +
+    ' must not be `null`.';
+  const message1 = getPropTypeWarningMessage(
+    propTypes,
+    {testProp: null},
+    'testComponent'
+  );
+  expect(message1).toContain(mustNotBeNullMsg);
+
+  const message2 = getPropTypeWarningMessage(
+    propTypes,
+    {testProp: undefined},
+    'testComponent'
+  );
+  expect(message2).toBe(null);
+}
+
 function expectThrowsInDevelopment(declaration, value) {
   resetWarningCache();
   var props = {testProp: value};
@@ -214,6 +235,10 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.string, undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(PropTypes.string.notNull);
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(PropTypes.string.isRequired);
     });
@@ -278,6 +303,10 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.any, undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(PropTypes.any.notNull);
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(PropTypes.any.isRequired);
     });
@@ -372,6 +401,12 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.arrayOf(PropTypes.number), undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(
+        PropTypes.arrayOf(PropTypes.number).notNull
+      );
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(
         PropTypes.arrayOf(PropTypes.number).isRequired,
@@ -441,6 +476,10 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.element, undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(PropTypes.element.notNull);
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(PropTypes.element.isRequired);
     });
@@ -540,6 +579,10 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.instanceOf(String), undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(PropTypes.instanceOf(String).notNull);
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(PropTypes.instanceOf(String).isRequired);
     });
@@ -636,6 +679,10 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.node, undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(PropTypes.node.notNull);
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(PropTypes.node.isRequired);
     });
@@ -753,6 +800,12 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.objectOf(PropTypes.number), undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(
+        PropTypes.objectOf(PropTypes.number).notNull
+      );
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(
         PropTypes.objectOf(PropTypes.number).isRequired,
@@ -830,6 +883,10 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckPass(PropTypes.oneOf(['red', 'blue']), undefined);
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(PropTypes.oneOf(['red', 'blue']).notNull);
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(PropTypes.oneOf(['red', 'blue']).isRequired);
     });
@@ -919,6 +976,12 @@ describe('PropTypesDevelopmentStandalone', () => {
       );
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(
+        PropTypes.oneOfType([PropTypes.string, PropTypes.number]).notNull
+      );
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(
         PropTypes.oneOfType([PropTypes.string, PropTypes.number]).isRequired,
@@ -1017,6 +1080,12 @@ describe('PropTypesDevelopmentStandalone', () => {
       );
     });
 
+    it('should warn when null is not allowed', () => {
+      typeCheckNullFail(
+        PropTypes.shape({key: PropTypes.number}).notNull
+      );
+    });
+
     it('should warn for missing required values', () => {
       typeCheckFailRequiredValues(
         PropTypes.shape({key: PropTypes.number}).isRequired,
diff --git a/factoryWithTypeCheckers.js b/factoryWithTypeCheckers.js
index 4da647e..c38e3ac 100644
--- a/factoryWithTypeCheckers.js
+++ b/factoryWithTypeCheckers.js
@@ -150,7 +150,7 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
       var manualPropTypeCallCache = {};
       var manualPropTypeWarningCount = 0;
     }
-    function checkType(isRequired, props, propName, componentName, location, propFullName, secret) {
+    function checkType(isRequired, notNull, props, propName, componentName, location, propFullName, secret) {
       componentName = componentName || ANONYMOUS;
       propFullName = propFullName || propName;
 
@@ -192,6 +192,8 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
             return new PropTypeError('The ' + location + ' `' + propFullName + '` is marked as required ' + ('in `' + componentName + '`, but its value is `null`.'));
           }
           return new PropTypeError('The ' + location + ' `' + propFullName + '` is marked as required in ' + ('`' + componentName + '`, but its value is `undefined`.'));
+        } else if (notNull && props[propName] === null) {
+          return new PropTypeError('The ' + location + ' `' + propFullName + '` ' + ('in `' + componentName + '` must not be `null`.'));
         }
         return null;
       } else {
@@ -199,8 +201,9 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
       }
     }
 
-    var chainedCheckType = checkType.bind(null, false);
-    chainedCheckType.isRequired = checkType.bind(null, true);
+    var chainedCheckType = checkType.bind(null, false, false);
+    chainedCheckType.isRequired = checkType.bind(null, true, true);
+    chainedCheckType.notNull = checkType.bind(null, false, true);
 
     return chainedCheckType;
   }