diff --git a/core/src/main/java/hudson/maven/MavenBuild.java b/core/src/main/java/hudson/maven/MavenBuild.java
index 3156afc6697c2325caed329f96e46ac441beeb09..8e1ed8adf271758661bf980dd97ab2c032bf1b49 100644
--- a/core/src/main/java/hudson/maven/MavenBuild.java
+++ b/core/src/main/java/hudson/maven/MavenBuild.java
@@ -301,7 +301,8 @@ public class MavenBuild extends AbstractBuild<MavenModule,MavenBuild> {
                 return launcher.launchChannel(buildMavenCmdLine(listener).toCommandArray(),
                     out, null, envVars);
             } catch (IOException e) {
-                if(e.getMessage().contains("java: not found")) {
+                String msg = e.getMessage();
+                if(msg!=null && msg.contains("java: not found")) {
                     // diagnose issue #659
                     JDK jdk = getParent().getParent().getJDK();
                     if(jdk==null)