diff --git a/logback-core/src/test/java/ch/qos/logback/core/appender/FileAppenderTest.java b/logback-core/src/test/java/ch/qos/logback/core/appender/FileAppenderTest.java
index d84beff71d47ec9744639dfc8de339a2c49762d0..eb6ee5ac0381fbfd3a1aa5af19b3600409b78d9c 100644
--- a/logback-core/src/test/java/ch/qos/logback/core/appender/FileAppenderTest.java
+++ b/logback-core/src/test/java/ch/qos/logback/core/appender/FileAppenderTest.java
@@ -133,9 +133,11 @@ public class FileAppenderTest extends AbstractAppenderTest<Object> {
   
   @Test
   public void fileNameCollision() {
+      String fileName = CoreTestConstants.OUTPUT_DIR_PREFIX + diff+ "fileNameCollision";
+      
       FileAppender<Object> appender0 = new FileAppender<Object>();
       appender0.setName("FA0");
-      appender0.setFile("X");
+      appender0.setFile(fileName);
       appender0.setContext(context);
       appender0.setEncoder(new DummyEncoder<Object>());
       appender0.start();
@@ -143,7 +145,7 @@ public class FileAppenderTest extends AbstractAppenderTest<Object> {
       
       FileAppender<Object> appender1 = new FileAppender<Object>();
       appender1.setName("FA1");
-      appender1.setFile("X");
+      appender1.setFile(fileName);
       appender1.setContext(context);
       appender1.setEncoder(new DummyEncoder<Object>());
       appender1.start();
diff --git a/logback-core/src/test/java/ch/qos/logback/core/rolling/RollingFileAppenderTest.java b/logback-core/src/test/java/ch/qos/logback/core/rolling/RollingFileAppenderTest.java
index e7f261f57d2aaa2c3def1fb1ab8c0625b3ef1ead..23499520447c33386003b23fadeb2973f5597f49 100755
--- a/logback-core/src/test/java/ch/qos/logback/core/rolling/RollingFileAppenderTest.java
+++ b/logback-core/src/test/java/ch/qos/logback/core/rolling/RollingFileAppenderTest.java
@@ -13,10 +13,18 @@
  */
 package ch.qos.logback.core.rolling;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
 import ch.qos.logback.core.Appender;
 import ch.qos.logback.core.Context;
 import ch.qos.logback.core.ContextBase;
-import ch.qos.logback.core.FileAppender;
 import ch.qos.logback.core.appender.AbstractAppenderTest;
 import ch.qos.logback.core.encoder.DummyEncoder;
 import ch.qos.logback.core.status.Status;
@@ -25,12 +33,6 @@ import ch.qos.logback.core.testUtil.RandomUtil;
 import ch.qos.logback.core.util.CoreTestConstants;
 import ch.qos.logback.core.util.StatusPrinter;
 
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
-
-import static org.junit.Assert.*;
-
 public class RollingFileAppenderTest extends AbstractAppenderTest<Object> {
 
   RollingFileAppender<Object> rfa = new RollingFileAppender<Object>();
@@ -229,13 +231,15 @@ public class RollingFileAppenderTest extends AbstractAppenderTest<Object> {
 
   @Test
   public void collidingFileNamePattern() {
+    String filenamePattern = CoreTestConstants.OUTPUT_DIR_PREFIX + diff+ "-collision-%d.log.zip";
+      
     RollingFileAppender<Object> appender0 = new RollingFileAppender<Object>();
     appender0.setName("FA0");
     appender0.setContext(context);
     appender0.setEncoder(new DummyEncoder<Object>());
     TimeBasedRollingPolicy<Object> tbrp0 = new TimeBasedRollingPolicy<Object>();
     tbrp0.setContext(context);
-    tbrp0.setFileNamePattern(CoreTestConstants.OUTPUT_DIR_PREFIX + "collision-%d.log.zip");
+    tbrp0.setFileNamePattern(filenamePattern);
     tbrp0.setParent(appender0);
     tbrp0.start();
     appender0.setRollingPolicy(tbrp0);
@@ -251,7 +255,7 @@ public class RollingFileAppenderTest extends AbstractAppenderTest<Object> {
     appender1.setEncoder(new DummyEncoder<Object>());
     TimeBasedRollingPolicy<Object> tbrp1 = new TimeBasedRollingPolicy<Object>();
     tbrp1.setContext(context);
-    tbrp1.setFileNamePattern(CoreTestConstants.OUTPUT_DIR_PREFIX + "collision-%d.log.zip");
+    tbrp1.setFileNamePattern(filenamePattern);
     tbrp1.setParent(appender1);
     tbrp1.start();
     appender1.setRollingPolicy(tbrp1);