diff --git a/test/401-optimizing-compiler/src/Main.java b/test/401-optimizing-compiler/src/Main.java
index 07c407b..7c3fd25 100644
--- a/test/401-optimizing-compiler/src/Main.java
+++ b/test/401-optimizing-compiler/src/Main.java
@@ -94,6 +94,14 @@
       exception = e;
     }
 
+    // Test that we do NPE checks on array length.
+    exception = null;
+    try {
+      $opt$ArrayLengthOfNull(null);
+    } catch (NullPointerException e) {
+      exception = e;
+    }
+
     if (exception == null) {
       throw new Error("Missing NullPointerException");
     }
@@ -218,5 +226,9 @@
     return 42;
   }
 
+  public static int $opt$ArrayLengthOfNull(int[] array) {
+    return array.length;
+  }
+
   Object o;
 }