diff --git a/app/test/processing/app/tools/ZipDeflaterTest.java b/app/test/processing/app/tools/ZipDeflaterTest.java
index 21f28cc29..e77aa830a 100644
--- a/app/test/processing/app/tools/ZipDeflaterTest.java
+++ b/app/test/processing/app/tools/ZipDeflaterTest.java
@@ -30,6 +30,8 @@
 package processing.app.tools;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertNotNull;
 
 import java.io.File;
 import java.util.Arrays;
@@ -57,11 +59,17 @@ public class ZipDeflaterTest {
     new ZipDeflater(file, destFolder).deflate();
 
     String[] files = destFolder.list();
+    assertNotNull(files);
     assertEquals(1, files.length);
     assertEquals("Test2", files[0]);
 
-    file = destFolder.listFiles()[0];
+    File[] destFolders = destFolder.listFiles();
+    assertNotNull(destFolders);
+    assertTrue(destFolders.length > 0);
+    file = destFolders[0];
+    assertNotNull(file);
     files = file.list();
+    assertNotNull(files);
     assertEquals(5, files.length);
     Arrays.sort(files);
     assertEquals("Test.cpp", files[0]);
@@ -77,11 +85,17 @@ public class ZipDeflaterTest {
     new ZipDeflater(file, destFolder).deflate();
 
     String[] files = destFolder.list();
+    assertNotNull(files);
     assertEquals(1, files.length);
     assertEquals("Test", files[0]);
 
-    file = destFolder.listFiles()[0];
+    File[] destFolders = destFolder.listFiles();
+    assertNotNull(destFolders);
+    assertTrue(destFolders.length > 0);
+    file = destFolders[0];
+    assertNotNull(file);
     files = file.list();
+    assertNotNull(files);
     assertEquals(5, files.length);
     Arrays.sort(files);
     assertEquals("Test.cpp", files[0]);
@@ -97,11 +111,17 @@ public class ZipDeflaterTest {
     new ZipDeflater(file, destFolder).deflate();
 
     String[] files = destFolder.list();
+    assertNotNull(files);
     assertEquals(1, files.length);
     assertEquals("Keypad", files[0]);
 
-    file = destFolder.listFiles()[0];
+    File[] destFolders = destFolder.listFiles();
+    assertNotNull(destFolders);
+    assertTrue(destFolders.length > 0);
+    file = destFolders[0];
+    assertNotNull(file);
     files = file.list();
+    assertNotNull(files);
     assertEquals(4, files.length);
     Arrays.sort(files);
     assertEquals("Keypad.cpp", files[0]);
@@ -110,6 +130,7 @@ public class ZipDeflaterTest {
     assertEquals("keywords.txt", files[3]);
 
     files = new File(file, "examples").list();
+    assertNotNull(files);
     assertEquals(4, files.length);
     Arrays.sort(files);
     assertEquals("CustomKeypad", files[0]);
@@ -124,11 +145,17 @@ public class ZipDeflaterTest {
     new ZipDeflater(file, destFolder).deflate();
 
     String[] files = destFolder.list();
+    assertNotNull(files);
     assertEquals(1, files.length);
     assertEquals("Keypad_with_hidden_files", files[0]);
 
-    file = destFolder.listFiles()[0];
+    File[] destFolders = destFolder.listFiles();
+    assertNotNull(destFolders);
+    assertTrue(destFolders.length > 0);
+    file = destFolders[0];
+    assertNotNull(file);
     files = file.list();
+    assertNotNull(files);
     assertEquals(4, files.length);
   }