diff --git a/updateHostsFile.py b/updateHostsFile.py
index 15de680e8..cff6fe561 100644
--- a/updateHostsFile.py
+++ b/updateHostsFile.py
@@ -292,9 +292,12 @@ def removeDupsAndExcl(mergeFile):
         os.makedirs(outputPath)
 
     # Another mode is required to read and write the file in Python 3
-    finalFile = open(os.path.join(outputPath, 'hosts'), 'r+')
-    mergeFile.seek(0) # reset file pointer
+    if Python3:
+        finalFile = open(os.path.join(outputPath, 'hosts'), 'w+b')
+    else:
+        finalFile = open(os.path.join(outputPath, 'hosts'), 'w+')
 
+    mergeFile.seek(0) # reset file pointer
     hostnames = set()
     hostnames.add("localhost")
     hostnames.add("localhost.localdomain")