diff --git a/core/src/main/java/hudson/matrix/MatrixBuild.java b/core/src/main/java/hudson/matrix/MatrixBuild.java
index bcef17f8887d..5675842311e0 100644
--- a/core/src/main/java/hudson/matrix/MatrixBuild.java
+++ b/core/src/main/java/hudson/matrix/MatrixBuild.java
@@ -368,7 +368,8 @@ protected Result doRun(BuildListener listener) throws Exception {
                     final int n = getNumber();
                     for (MatrixConfiguration c : activeConfigurations) {
                         for (Item i : q.getItems(c)) {
-                            if (i.getAction(ParentBuildAction.class).parent==getBuild()) {
+                            ParentBuildAction a = i.getAction(ParentBuildAction.class);
+                            if (a!=null && a.parent==getBuild()) {
                                 q.cancel(i);
                                 logger.println(Messages.MatrixBuild_Cancelled(ModelHyperlinkNote.encodeTo(c)));
                             }