diff --git a/modules/javafx.web/src/main/java/javafx/scene/web/WebView.java b/modules/javafx.web/src/main/java/javafx/scene/web/WebView.java
index 8889a6f88c8..5a78739cff2 100644
--- a/modules/javafx.web/src/main/java/javafx/scene/web/WebView.java
+++ b/modules/javafx.web/src/main/java/javafx/scene/web/WebView.java
@@ -994,12 +994,13 @@ private void processMouseEvent(MouseEvent ev) {
         }
 
         final Integer id = idMap.get(type);
-        if (id == null) {
+        final Integer button = idMap.get(ev.getButton());
+        if (id == null || button == null) {
             // not supported by webkit
             return;
         }
         WCMouseEvent mouseEvent =
-                new WCMouseEvent(id, idMap.get(ev.getButton()),
+                new WCMouseEvent(id, button,
                     ev.getClickCount(), (int) x, (int) y,
                     (int) screenX, (int) screenY,
                     System.currentTimeMillis(),
diff --git a/modules/javafx.web/src/test/java/test/javafx/scene/web/WebViewTest.java b/modules/javafx.web/src/test/java/test/javafx/scene/web/WebViewTest.java
index f47667cdcaf..0b97ce551ec 100644
--- a/modules/javafx.web/src/test/java/test/javafx/scene/web/WebViewTest.java
+++ b/modules/javafx.web/src/test/java/test/javafx/scene/web/WebViewTest.java
@@ -30,7 +30,9 @@
 import java.io.File;
 import java.util.concurrent.FutureTask;
 
-import javafx.application.Platform;
+import javafx.event.Event;
+import javafx.scene.input.MouseButton;
+import javafx.scene.input.MouseEvent;
 import javafx.scene.web.WebEngineShim;
 import javafx.scene.web.WebView;
 
@@ -54,6 +56,18 @@ public class WebViewTest extends TestBase {
         checkZoom(view, ZOOM);
     }
 
+    @Test public void testForwardMouseButton() {
+        WebView view = getView();
+        Event forward = new MouseEvent(MouseEvent.MOUSE_PRESSED, 0, 0, 0, 0, MouseButton.FORWARD, 1, false, false, false, false, false, false, false, false, true, true, false, true, null);
+        view.fireEvent(forward);    // must not throw NullPointerException (JDK-8236912)
+    }
+
+    @Test public void testBackMouseButton() {
+        WebView view = getView();
+        Event back = new MouseEvent(MouseEvent.MOUSE_PRESSED, 0, 0, 0, 0, MouseButton.BACK, 1, false, false, false, false, false, false, false, true, false, true, false, true, null);
+        view.fireEvent(back);    // must not throw NullPointerException (JDK-8236912)
+    }
+
     void checkFontScale(WebView view, float scale) {
         assertEquals("WebView.fontScale", scale, view.getFontScale(), DELTA);
         assertEquals("WebPage.zoomFactor",