diff --git a/lucene/core/src/test/org/apache/lucene/store/TestDirectory.java b/lucene/core/src/test/org/apache/lucene/store/TestDirectory.java
index 92425bf4e3a..cd9362c69cb 100644
--- a/lucene/core/src/test/org/apache/lucene/store/TestDirectory.java
+++ b/lucene/core/src/test/org/apache/lucene/store/TestDirectory.java
@@ -37,6 +37,12 @@ public class TestDirectory extends BaseDirectoryTestCase {
     }
   }
 
+  // we wrap the directory in slow stuff, so only run nightly
+  @Override @Nightly
+  public void testThreadSafety() throws Exception {
+    super.testThreadSafety();
+  }
+
   // Test that different instances of FSDirectory can coexist on the same
   // path, can read, write, and lock files.
   public void testDirectInstantiation() throws Exception {
diff --git a/lucene/core/src/test/org/apache/lucene/store/TestFileSwitchDirectory.java b/lucene/core/src/test/org/apache/lucene/store/TestFileSwitchDirectory.java
index 8adf91250b2..3b37d26b829 100644
--- a/lucene/core/src/test/org/apache/lucene/store/TestFileSwitchDirectory.java
+++ b/lucene/core/src/test/org/apache/lucene/store/TestFileSwitchDirectory.java
@@ -97,8 +97,7 @@ public class TestFileSwitchDirectory extends BaseDirectoryTestCase {
   private Directory newFSSwitchDirectory(File aDir, File bDir, Set<String> primaryExtensions) throws IOException {
     Directory a = new SimpleFSDirectory(aDir);
     Directory b = new SimpleFSDirectory(bDir);
-    FileSwitchDirectory switchDir = new FileSwitchDirectory(primaryExtensions, a, b, true);
-    return new MockDirectoryWrapper(random(), switchDir);
+    return new FileSwitchDirectory(primaryExtensions, a, b, true);
   }
   
   // LUCENE-3380 -- make sure we get exception if the directory really does not exist.
diff --git a/lucene/core/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java b/lucene/core/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java
index 50edf3f9e5e..b56324ab2c6 100644
--- a/lucene/core/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java
+++ b/lucene/core/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java
@@ -18,6 +18,7 @@ package org.apache.lucene.store;
  */
 
 import java.io.File;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -38,9 +39,12 @@ import org.apache.lucene.util.TestUtil;
 
 public class TestNRTCachingDirectory extends BaseDirectoryTestCase {
 
+  // TODO: RAMDir used here, because its still too slow to use e.g. SimpleFS
+  // for the threads tests... maybe because of the synchronization in listAll?
+  // would be good to investigate further...
   @Override
-  protected Directory getDirectory(File path) {
-    return new NRTCachingDirectory(newFSDirectory(path),
+  protected Directory getDirectory(File path) throws IOException {
+    return new NRTCachingDirectory(new RAMDirectory(),
                                    .1 + 2.0*random().nextDouble(),
                                    .1 + 5.0*random().nextDouble());
   }
diff --git a/lucene/core/src/test/org/apache/lucene/store/TestRateLimitedDirectoryWrapper.java b/lucene/core/src/test/org/apache/lucene/store/TestRateLimitedDirectoryWrapper.java
index d1031537237..238fac673cb 100644
--- a/lucene/core/src/test/org/apache/lucene/store/TestRateLimitedDirectoryWrapper.java
+++ b/lucene/core/src/test/org/apache/lucene/store/TestRateLimitedDirectoryWrapper.java
@@ -28,4 +28,10 @@ public class TestRateLimitedDirectoryWrapper extends BaseDirectoryTestCase {
     dir.setRateLimiter(limiter, IOContext.Context.MERGE);
     return dir;
   }
+
+  // since we are rate-limiting, this test gets pretty slow
+  @Override @Nightly
+  public void testThreadSafety() throws Exception {
+    super.testThreadSafety();
+  }
 }
diff --git a/lucene/test-framework/src/java/org/apache/lucene/store/BaseDirectoryTestCase.java b/lucene/test-framework/src/java/org/apache/lucene/store/BaseDirectoryTestCase.java
index 3600a62e23a..81007e29e9f 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/store/BaseDirectoryTestCase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/store/BaseDirectoryTestCase.java
@@ -51,13 +51,11 @@ public abstract class BaseDirectoryTestCase extends LuceneTestCase {
     }
   }
   
-  // test is occasionally very slow, i dont know why
-  // try this seed: 7D7E036AD12927F5:93333EF9E6DE44DE
-  @Nightly
   public void testThreadSafety() throws Exception {
-    final Directory raw = getDirectory(createTempDir("testThreadSafety"));
-    final BaseDirectoryWrapper dir = newDirectory(raw);
-    dir.setCheckIndexOnClose(false); // we arent making an index
+    final Directory dir = getDirectory(createTempDir("testThreadSafety"));
+    if (dir instanceof BaseDirectoryWrapper) {
+      ((BaseDirectoryWrapper)dir).setCheckIndexOnClose(false); // we arent making an index
+    }
     if (dir instanceof MockDirectoryWrapper) {
       ((MockDirectoryWrapper)dir).setThrottling(MockDirectoryWrapper.Throttling.NEVER); // makes this test really slow
     }
@@ -91,6 +89,7 @@ public abstract class BaseDirectoryTestCase extends LuceneTestCase {
     
     class TheThread2 extends Thread {
       private String name;
+      private volatile boolean stop;
 
       public TheThread2(String name) {
         this.name = name;
@@ -98,7 +97,7 @@ public abstract class BaseDirectoryTestCase extends LuceneTestCase {
       
       @Override
       public void run() {
-        for (int i = 0; i < 10000; i++) {
+        while (stop == false) {
           try {
             String[] files = dir.listAll();
             for (String file : files) {
@@ -109,7 +108,7 @@ public abstract class BaseDirectoryTestCase extends LuceneTestCase {
               } catch (FileNotFoundException | NoSuchFileException e) {
                 // ignore
               } catch (IOException e) {
-                if (e.getMessage().contains("still open for writing")) {
+                if (e.getMessage() != null && e.getMessage().contains("still open for writing")) {
                   // ignore
                 } else {
                   throw new RuntimeException(e);
@@ -132,10 +131,13 @@ public abstract class BaseDirectoryTestCase extends LuceneTestCase {
     theThread2.start();
     
     theThread.join();
+    
+    // after first thread is done, no sense in waiting on thread 2 
+    // to listFiles() and loop over and over
+    theThread2.stop = true;
     theThread2.join();
     
     dir.close();
-    raw.close();
   }
 
   /** LUCENE-1464: just creating a Directory should not
diff --git a/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java b/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java
index e1f237c4b4a..4a6df5e222f 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java
@@ -1099,11 +1099,11 @@ public abstract class LuceneTestCase extends Assert {
   }
   
   private static BaseDirectoryWrapper wrapDirectory(Random random, Directory directory, boolean bare) {
-    if (rarely(random)) {
+    if (rarely(random) && !bare) {
       directory = new NRTCachingDirectory(directory, random.nextDouble(), random.nextDouble());
     }
     
-    if (rarely(random)) { 
+    if (rarely(random) && !bare) { 
       final double maxMBPerSec = 10 + 5*(random.nextDouble()-0.5);
       if (LuceneTestCase.VERBOSE) {
         System.out.println("LuceneTestCase: will rate limit output IndexOutput to " + maxMBPerSec + " MB/sec");