diff --git a/src/main/java/org/ids_mannheim/TotalNGram.java b/src/main/java/org/ids_mannheim/TotalNGram.java
index 2774da4..fb0ea3e 100644
--- a/src/main/java/org/ids_mannheim/TotalNGram.java
+++ b/src/main/java/org/ids_mannheim/TotalNGram.java
@@ -105,18 +105,7 @@
         if ((output_fillename == null) || output_fillename.equals("-")) {
             output_stream = System.out;
         } else {
-            File f = new File(output_fillename);
-            try {
-                Files.createFile(f.toPath());
-            } catch (AccessDeniedException e) {
-                System.err.println("ERROR: Cannot write output file '" + output_fillename + "'");
-                System.exit(-1);
-            } catch (FileAlreadyExistsException e) {
-                if (!force_overwrite) {
-                    System.err.println("ERROR: '" + output_fillename + "' already exits. Use --force to overwrite.");
-                    System.exit(-1);
-                }
-            }
+            File f = Utils.createFile(output_fillename, force_overwrite);
             if (output_fillename.endsWith(".gz")) {
                 output_stream = new PrintStream(new ParallelGZIPOutputStream((new BufferedOutputStream(new FileOutputStream(f)))));
             } else {
diff --git a/src/main/java/org/ids_mannheim/Utils.java b/src/main/java/org/ids_mannheim/Utils.java
index 7d60dc9..3ac2966 100644
--- a/src/main/java/org/ids_mannheim/Utils.java
+++ b/src/main/java/org/ids_mannheim/Utils.java
@@ -1,10 +1,42 @@
 package org.ids_mannheim;
 
+import java.io.File;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.nio.file.AccessDeniedException;
+import java.nio.file.FileAlreadyExistsException;
+import java.nio.file.Files;
+
 public class Utils {
     public static String newExtension(String original, String newExtension) {
+        if(original.equals("-"))
+            throw new IllegalArgumentException("Cannot add a file name extension to stdout.");
         if (original.contains("."))
             return original.replaceFirst("(\\.[^.]*|\\.[^.]+\\.gz)$", "."+newExtension);
         else
             return original+".log";
     }
+
+    public static File createFile(String fname, boolean force_overwrite) {
+        File f = new File(fname);
+        try {
+            Files.createFile(f.toPath());
+        } catch (AccessDeniedException e) {
+            final String message = "ERROR: Cannot write file '" + fname + "'";
+            System.err.println(message);
+            TotalNGram.logger.severe(message);
+            System.exit(-1);
+        } catch (FileAlreadyExistsException e) {
+            if (!force_overwrite) {
+                final String message = "ERROR: '" + fname + "' already exits. Use --force to overwrite";
+                TotalNGram.logger.severe(message);
+                System.err.println(message);
+                System.exit(-1);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return f;
+    }
 }
+