diff --git a/src/ReactVersion.js b/src/ReactVersion.js
index 4972f9494..cf91b4c58 100644
--- a/src/ReactVersion.js
+++ b/src/ReactVersion.js
@@ -13,2 +13,2 @@
 
-module.exports = '15.6.0';
+module.exports = '15.6.1';
diff --git a/src/addons/link/ReactLink.js b/src/addons/link/ReactLink.js
index 273c4fdcc..d91345e69 100644
--- a/src/addons/link/ReactLink.js
+++ b/src/addons/link/ReactLink.js
@@ -36,4 +36,2 @@
 
-var React = require('React');
-
 /**
diff --git a/src/isomorphic/classic/types/__tests__/ReactPropTypes-test.js b/src/isomorphic/classic/types/__tests__/ReactPropTypes-test.js
index 092d2b6f8..c12cc1c29 100644
--- a/src/isomorphic/classic/types/__tests__/ReactPropTypes-test.js
+++ b/src/isomorphic/classic/types/__tests__/ReactPropTypes-test.js
@@ -91,3 +91,13 @@ function typeCheckPass(declaration, value) {
 
+function resetWarningCache() {
+  jest.resetModules();
+  PropTypes = require('ReactPropTypes');
+  React = require('React');
+  ReactFragment = require('ReactFragment');
+  ReactTestUtils = require('ReactTestUtils');
+  ReactPropTypesSecret = require('ReactPropTypesSecret');
+}
+
 function expectWarningInDevelopment(declaration, value) {
+  resetWarningCache();
   var props = {testProp: value};
@@ -107,7 +117,3 @@ describe('ReactPropTypes', () => {
   beforeEach(() => {
-    PropTypes = require('ReactPropTypes');
-    React = require('React');
-    ReactFragment = require('ReactFragment');
-    ReactTestUtils = require('ReactTestUtils');
-    ReactPropTypesSecret = require('ReactPropTypesSecret');
+    resetWarningCache();
   });
diff --git a/src/renderers/dom/client/inputValueTracking.js b/src/renderers/dom/client/inputValueTracking.js
index f5fa806e3..f0086f03a 100644
--- a/src/renderers/dom/client/inputValueTracking.js
+++ b/src/renderers/dom/client/inputValueTracking.js
@@ -64,6 +64,11 @@ var inputValueTracking = {
 
-    // if someone has already defined a value bail and don't track value
-    // will cause over reporting of changes, but it's better then a hard failure
-    // (needed for certain tests that spyOn input values)
-    if (node.hasOwnProperty(valueField)) {
+    // if someone has already defined a value or Safari, then bail
+    // and don't track value will cause over reporting of changes,
+    // but it's better then a hard failure
+    // (needed for certain tests that spyOn input values and Safari)
+    if (
+      node.hasOwnProperty(valueField) ||
+      typeof descriptor.get !== 'function' ||
+      typeof descriptor.set !== 'function'
+    ) {
       return;
diff --git a/src/renderers/dom/shared/CSSPropertyOperations.js b/src/renderers/dom/shared/CSSPropertyOperations.js
index 2bc2ae174..0af3b0980 100644
--- a/src/renderers/dom/shared/CSSPropertyOperations.js
+++ b/src/renderers/dom/shared/CSSPropertyOperations.js
@@ -130,6 +130,2 @@ if (__DEV__) {
   var warnValidStyle = function(name, value, component) {
-    // Don't warn for CSS variables
-    if (name.indexOf('--') === 0) {
-      return;
-    }
     var owner;
@@ -175,5 +171,8 @@ var CSSPropertyOperations = {
       }
+      var isCustomProperty = styleName.indexOf('--') === 0;
       var styleValue = styles[styleName];
       if (__DEV__) {
-        warnValidStyle(styleName, styleValue, component);
+        if (!isCustomProperty) {
+          warnValidStyle(styleName, styleValue, component);
+        }
       }
@@ -182,3 +181,8 @@ var CSSPropertyOperations = {
         serialized +=
-          dangerousStyleValue(styleName, styleValue, component) + ';';
+          dangerousStyleValue(
+            styleName,
+            styleValue,
+            component,
+            isCustomProperty,
+          ) + ';';
       }
@@ -210,4 +214,7 @@ var CSSPropertyOperations = {
       }
+      var isCustomProperty = styleName.indexOf('--') === 0;
       if (__DEV__) {
-        warnValidStyle(styleName, styles[styleName], component);
+        if (!isCustomProperty) {
+          warnValidStyle(styleName, styles[styleName], component);
+        }
       }
@@ -217,2 +224,3 @@ var CSSPropertyOperations = {
         component,
+        isCustomProperty,
       );
@@ -221,3 +229,3 @@ var CSSPropertyOperations = {
       }
-      if (styleName.indexOf('--') === 0) {
+      if (isCustomProperty) {
         style.setProperty(styleName, styleValue);
diff --git a/src/renderers/dom/shared/__tests__/CSSPropertyOperations-test.js b/src/renderers/dom/shared/__tests__/CSSPropertyOperations-test.js
index e383549ec..21029d00c 100644
--- a/src/renderers/dom/shared/__tests__/CSSPropertyOperations-test.js
+++ b/src/renderers/dom/shared/__tests__/CSSPropertyOperations-test.js
@@ -103,2 +103,10 @@ describe('CSSPropertyOperations', () => {
 
+  it('should create markup with unitless css custom property', () => {
+    expect(
+      CSSPropertyOperations.createMarkupForStyles({
+        '--foo': 5,
+      }),
+    ).toBe('--foo:5;');
+  });
+
   it('should set style attribute when styles exist', () => {
@@ -256,3 +264,3 @@ describe('CSSPropertyOperations', () => {
 
-  it('should not warn when setting CSS variables', () => {
+  it('should not warn when setting CSS custom properties', () => {
     class Comp extends React.Component {
@@ -269,2 +277,15 @@ describe('CSSPropertyOperations', () => {
   });
+
+  it('should not add units to CSS custom properties', () => {
+    class Comp extends React.Component {
+      render() {
+        return <div style={{'--foo': 5}} />;
+      }
+    }
+
+    var root = document.createElement('div');
+    ReactDOM.render(<Comp />, root);
+
+    expect(root.children[0].style.Foo).toEqual('5');
+  });
 });
diff --git a/src/renderers/dom/shared/dangerousStyleValue.js b/src/renderers/dom/shared/dangerousStyleValue.js
index 287a91f40..74e130dda 100644
--- a/src/renderers/dom/shared/dangerousStyleValue.js
+++ b/src/renderers/dom/shared/dangerousStyleValue.js
@@ -29,3 +29,3 @@ var styleWarnings = {};
  */
-function dangerousStyleValue(name, value, component) {
+function dangerousStyleValue(name, value, component, isCustomProperty) {
   // Note that we've removed escapeTextForBrowser() calls here since the
@@ -47,2 +47,3 @@ function dangerousStyleValue(name, value, component) {
   if (
+    isCustomProperty ||
     isNonNumeric ||