diff --git a/com.ibm.wala.cast.js.nodejs/src/com/ibm/wala/cast/js/nodejs/NodejsRequiredCoreModule.java b/com.ibm.wala.cast.js.nodejs/src/com/ibm/wala/cast/js/nodejs/NodejsRequiredCoreModule.java
index 2b8326013..c77b67a23 100644
--- a/com.ibm.wala.cast.js.nodejs/src/com/ibm/wala/cast/js/nodejs/NodejsRequiredCoreModule.java
+++ b/com.ibm.wala.cast.js.nodejs/src/com/ibm/wala/cast/js/nodejs/NodejsRequiredCoreModule.java
@@ -13,6 +13,7 @@ package com.ibm.wala.cast.js.nodejs;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.Files;
 import java.util.Arrays;
 import java.util.Set;
 
@@ -52,7 +53,8 @@ public class NodejsRequiredCoreModule extends NodejsRequiredSourceModule {
 
 	}
 	public static NodejsRequiredCoreModule make(String name) throws IOException {
-		File file = new File(System.getProperty("java.io.tmpdir"), name+".js");
+		File file = Files.createTempFile(name, ".js").toFile();
+		file.deleteOnExit();
 		TemporaryFile.streamToFile(file, getModule(name));
 		SourceFileModule sourceFileModule = CAstCallGraphUtil.makeSourceModule(file.toURI().toURL(), file.getName());
 		return new NodejsRequiredCoreModule(file, sourceFileModule);
diff --git a/com.ibm.wala.core.tests/src/com/ibm/wala/core/tests/shrike/DynamicCallGraphTestBase.java b/com.ibm.wala.core.tests/src/com/ibm/wala/core/tests/shrike/DynamicCallGraphTestBase.java
index 2a9807a83..8635d5173 100644
--- a/com.ibm.wala.core.tests/src/com/ibm/wala/core/tests/shrike/DynamicCallGraphTestBase.java
+++ b/com.ibm.wala.core.tests/src/com/ibm/wala/core/tests/shrike/DynamicCallGraphTestBase.java
@@ -13,9 +13,9 @@ package com.ibm.wala.core.tests.shrike;
 
 import java.io.BufferedReader;
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -65,17 +65,26 @@ public abstract class DynamicCallGraphTestBase extends WalaTestCase {
   
   private boolean instrumentedJarBuilt = false;
   
-  private String instrumentedJarLocation = System.getProperty("java.io.tmpdir") + File.separator + "test.jar";
+  private java.nio.file.Path instrumentedJarLocation;
 
-  private String cgLocation = System.getProperty("java.io.tmpdir") + File.separator + "cg.txt";
+  private java.nio.file.Path cgLocation;
+
+  protected DynamicCallGraphTestBase() {
+      try {
+          instrumentedJarLocation = Files.createTempFile("wala-test", ".jar");
+	  instrumentedJarLocation.toFile().deleteOnExit();
+          cgLocation = Files.createTempFile("cg", ".txt");
+	  cgLocation.toFile().deleteOnExit();
+      } catch (IOException problem) {
+          throw new RuntimeException(problem);
+      }
+  }
 
   protected void instrument(String testJarLocation) throws IOException, ClassNotFoundException, InvalidClassFileException, FailureException {
     if (! instrumentedJarBuilt) {
       System.err.println("core data jar to instrument: " + testJarLocation);
       
-      if (new File(instrumentedJarLocation).exists()) {
-        assert new File(instrumentedJarLocation).delete();
-      }
+      Files.deleteIfExists(instrumentedJarLocation);
       
       String rtJar = null;
       for(String jar : WalaProperties.getJ2SEJarFiles()) {
@@ -85,7 +94,7 @@ public abstract class DynamicCallGraphTestBase extends WalaTestCase {
       }
       
       List<String> args = new ArrayList<>();
-      args.addAll(Arrays.asList(testJarLocation, "-o", instrumentedJarLocation));
+      args.addAll(Arrays.asList(testJarLocation, "-o", instrumentedJarLocation.toString()));
       if (rtJar != null) {
         args.addAll(Arrays.asList("--rt-jar", rtJar));
       }
@@ -93,14 +102,16 @@ public abstract class DynamicCallGraphTestBase extends WalaTestCase {
         args.add("--patch-calls");
       }
       OfflineDynamicCallGraph.main(args.toArray(new String[ args.size() ]));
-      Assert.assertTrue("expected to create /tmp/test.jar", new File(instrumentedJarLocation).exists());   
+      Assert.assertTrue("expected to create " + instrumentedJarLocation, Files.exists(instrumentedJarLocation));
       instrumentedJarBuilt = true;
     }
   }
   
   protected void run(String mainClass, String exclusionsFile, String... args) throws IOException, SecurityException, IllegalArgumentException, InterruptedException {
     Project p = new Project();
-    p.setBaseDir(new File(System.getProperty("java.io.tmpdir")));
+    final File projectDir = Files.createTempDirectory("wala-test").toFile();
+    projectDir.deleteOnExit();
+    p.setBaseDir(projectDir);
     p.init();
     p.fireBuildStarted();
 
@@ -125,9 +136,7 @@ public abstract class DynamicCallGraphTestBase extends WalaTestCase {
     childJvm.setFailonerror(true);
     childJvm.setFork(true);
     
-    if (new File(cgLocation).exists()) {
-      new File(cgLocation).delete();
-    }
+    Files.deleteIfExists(cgLocation);
     
     childJvm.init();
     String commandLine = childJvm.getCommandLine().toString();
@@ -135,7 +144,7 @@ public abstract class DynamicCallGraphTestBase extends WalaTestCase {
     Process x = Runtime.getRuntime().exec(commandLine);
     x.waitFor();
     
-    Assert.assertTrue("expected to create call graph", new File(cgLocation).exists());
+    Assert.assertTrue("expected to create call graph", Files.exists(cgLocation));
   }
    
   interface EdgesTest {
@@ -186,7 +195,7 @@ public abstract class DynamicCallGraphTestBase extends WalaTestCase {
  
   protected void check(CallGraph staticCG, EdgesTest test, Predicate<MethodReference> filter) throws IOException {
     int lines = 0;
-    try (final BufferedReader dynamicEdgesFile = new BufferedReader(new InputStreamReader(new GZIPInputStream(new FileInputStream(cgLocation))))) {
+    try (final BufferedReader dynamicEdgesFile = new BufferedReader(new InputStreamReader(new GZIPInputStream(Files.newInputStream(cgLocation))))) {
       String line;
       loop: while ((line = dynamicEdgesFile.readLine()) != null) {
         if (line.startsWith("call to") || line.startsWith("return from")) {
diff --git a/com.ibm.wala.dalvik/src/com/ibm/wala/dalvik/classLoader/DexFileModule.java b/com.ibm.wala.dalvik/src/com/ibm/wala/dalvik/classLoader/DexFileModule.java
index 42e294fd5..c20383b3d 100644
--- a/com.ibm.wala.dalvik/src/com/ibm/wala/dalvik/classLoader/DexFileModule.java
+++ b/com.ibm.wala.dalvik/src/com/ibm/wala/dalvik/classLoader/DexFileModule.java
@@ -49,6 +49,7 @@ package com.ibm.wala.dalvik.classLoader;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.Files;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -83,12 +84,12 @@ public class DexFileModule implements Module {
     	}
     }
     
-    private static File tf(JarFile f) {
+    private static File tf(JarFile f) throws IOException {
     	String name = f.getName();
     	if (name.indexOf('/') >= 0) {
     		name = name.substring(name.lastIndexOf('/')+1);
     	}
-    	File tf = new File(System.getProperty("java.io.tmpdir") + "/" + name + "_classes.dex");
+    	File tf = Files.createTempFile("name", "_classes.dex").toFile();
     	tf.deleteOnExit();
     	System.err.println("using " + tf);
     	return tf;
diff --git a/com.ibm.wala.shrike/src/com/ibm/wala/shrike/instrumentation/CodeScraper.java b/com.ibm.wala.shrike/src/com/ibm/wala/shrike/instrumentation/CodeScraper.java
index 9a57d792f..7dfbe1dc8 100644
--- a/com.ibm.wala.shrike/src/com/ibm/wala/shrike/instrumentation/CodeScraper.java
+++ b/com.ibm.wala.shrike/src/com/ibm/wala/shrike/instrumentation/CodeScraper.java
@@ -1,11 +1,12 @@
 package com.ibm.wala.shrike.instrumentation;
 
-import java.io.File;
-import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.OutputStream;
 import java.lang.instrument.ClassFileTransformer;
 import java.lang.instrument.IllegalClassFormatException;
 import java.lang.instrument.Instrumentation;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.security.ProtectionDomain;
 
 import com.ibm.wala.shrikeCT.ClassReader;
@@ -15,11 +16,16 @@ import com.ibm.wala.shrikeCT.SourceFileReader;
 
 public class CodeScraper implements ClassFileTransformer {
 
-  private static final String prefix = System.getProperty("java.io.tmpdir") + File.separator + "loggedClasses" + File.separator + System.currentTimeMillis();
+  private static final Path prefix;
   
   static {
+    try {
+      prefix = Files.createTempDirectory("loggedClasses");
+      prefix.toFile().deleteOnExit();
+    } catch (final IOException problem) {
+      throw new RuntimeException(problem);
+    }
     System.err.println("scraping to " + prefix);
-    (new File(prefix)).mkdirs();
   }
   
   @Override
@@ -38,9 +44,8 @@ public class CodeScraper implements ClassFileTransformer {
         }
       }
       if (className == null || sourceFile == null || !sourceFile.endsWith("java") || true) try {
-        String log = prefix + File.separator + reader.getName() + ".class";
-        (new File(log)).getParentFile().mkdirs();
-        try (final FileOutputStream f = new FileOutputStream(log)) {
+        Path log = prefix.resolve(reader.getName() + ".class");
+        try (final OutputStream f = Files.newOutputStream(log)) {
           f.write(classfileBuffer);
         }
       } catch (IOException e) {