diff -r 56a05d7bb395 src/org/python/core/io/FileIO.java
--- a/src/org/python/core/io/FileIO.java	Fri Aug 23 11:59:59 2013 -0700
+++ b/src/org/python/core/io/FileIO.java	Tue Sep 03 14:07:10 2013 -0700
@@ -72,7 +72,7 @@
         File absPath = new RelativeFile(name.toString());
 
         try {
-            if (appending && !(reading || plus)) {
+            if ((appending && !(reading || plus)) || (writing && !reading)) {
                 // Take advantage of FileOutputStream's append mode
                 fromFileOutputStream(absPath);
             } else {
@@ -181,7 +181,7 @@
      * @param absPath The absolute path File to open
      */
     private void fromFileOutputStream(File absPath) throws FileNotFoundException {
-        fileOutputStream = new FileOutputStream(absPath, true);
+        fileOutputStream = new FileOutputStream(absPath, appending);
         fileChannel = fileOutputStream.getChannel();
     }