diff --git a/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/Generator.java b/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/Generator.java
index d683241..8465203 100644
--- a/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/Generator.java
+++ b/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/Generator.java
@@ -5,6 +5,10 @@ import ch.fritteli.labyrinth.generator.model.Labyrinth;
 import ch.fritteli.labyrinth.generator.model.Position;
 import ch.fritteli.labyrinth.generator.model.Tile;
 import io.vavr.control.Option;
+import java.awt.BasicStroke;
+import java.awt.Color;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.Value;
@@ -16,18 +20,15 @@ import org.apache.pdfbox.pdmodel.PDPageContentStream;
 import org.apache.pdfbox.pdmodel.common.PDRectangle;
 import org.jetbrains.annotations.Nullable;
 
-import java.awt.*;
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-
 @RequiredArgsConstructor
 @Slf4j
 class Generator {
+
     @NonNull
     private final Labyrinth labyrinth;
 
     @NonNull
-    public byte[] generate() {
+    public ByteArrayOutputStream generate() {
         final float pageWidth = this.labyrinth.getWidth() * PDFRenderer.SCALE + 2 * PDFRenderer.MARGIN;
         final float pageHeight = this.labyrinth.getHeight() * PDFRenderer.SCALE + 2 * PDFRenderer.MARGIN;
 
@@ -39,7 +40,8 @@ class Generator {
         final PDPage solutionPage = new PDPage(new PDRectangle(pageWidth, pageHeight));
         pdDocument.addPage(puzzlePage);
         pdDocument.addPage(solutionPage);
-        try (final PDPageContentStream puzzlePageContentStream = new PDPageContentStream(pdDocument, puzzlePage); final PDPageContentStream solutionPageContentStream = new PDPageContentStream(pdDocument, solutionPage)) {
+        try (final PDPageContentStream puzzlePageContentStream = new PDPageContentStream(pdDocument, puzzlePage);
+                final PDPageContentStream solutionPageContentStream = new PDPageContentStream(pdDocument, solutionPage)) {
             setUpPageContentStream(puzzlePageContentStream);
             setUpPageContentStream(solutionPageContentStream);
             this.drawHorizontalLines(puzzlePageContentStream, solutionPageContentStream);
@@ -55,7 +57,7 @@ class Generator {
         } catch (IOException e) {
             log.error("Error while writing PDF data", e);
         }
-        return output.toByteArray();
+        return output;
     }
 
     private void setUpPageContentStream(@NonNull final PDPageContentStream pageContentStream) throws IOException {
@@ -241,6 +243,7 @@ class Generator {
 
     @Value
     private class Coordinate {
+
         float x;
         float y;
 
@@ -268,6 +271,7 @@ class Generator {
 
     @Value
     private class SolutionCoordinate {
+
         float x;
         float y;
 
diff --git a/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/PDFRenderer.java b/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/PDFRenderer.java
index c9ff88a..087db76 100644
--- a/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/PDFRenderer.java
+++ b/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdf/PDFRenderer.java
@@ -2,9 +2,10 @@ package ch.fritteli.labyrinth.generator.renderer.pdf;
 
 import ch.fritteli.labyrinth.generator.model.Labyrinth;
 import ch.fritteli.labyrinth.generator.renderer.Renderer;
+import java.io.ByteArrayOutputStream;
 import lombok.NonNull;
 
-public class PDFRenderer implements Renderer<byte[]> {
+public class PDFRenderer implements Renderer<ByteArrayOutputStream> {
     static final float MARGIN = 10;
     static final float SCALE = 10;
 
@@ -18,7 +19,7 @@ public class PDFRenderer implements Renderer<byte[]> {
 
     @NonNull
     @Override
-    public byte[] render(@NonNull final Labyrinth labyrinth) {
+    public ByteArrayOutputStream render(@NonNull final Labyrinth labyrinth) {
         final Generator generator = new Generator(labyrinth);
         return generator.generate();
     }
diff --git a/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdffile/PDFFileRenderer.java b/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdffile/PDFFileRenderer.java
index a6753e0..7b73d05 100644
--- a/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdffile/PDFFileRenderer.java
+++ b/src/main/java/ch/fritteli/labyrinth/generator/renderer/pdffile/PDFFileRenderer.java
@@ -5,17 +5,18 @@ import ch.fritteli.labyrinth.generator.renderer.Renderer;
 import ch.fritteli.labyrinth.generator.renderer.pdf.PDFRenderer;
 import io.vavr.control.Option;
 import io.vavr.control.Try;
-import lombok.NonNull;
-import lombok.extern.slf4j.Slf4j;
-
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.NoSuchElementException;
+import lombok.NonNull;
+import lombok.extern.slf4j.Slf4j;
 
 @Slf4j
 public class PDFFileRenderer implements Renderer<Path> {
+
     @NonNull
     private static final PDFRenderer PDF_RENDERER = PDFRenderer.newInstance();
     @NonNull
@@ -55,13 +56,13 @@ public class PDFFileRenderer implements Renderer<Path> {
                 throw new IllegalArgumentException("Cannot write to target file.", e);
             }
         }
-        final byte[] bytes = PDF_RENDERER.render(labyrinth);
-        final Path targetFile = this.targetFile.get();
+        final ByteArrayOutputStream bytes = PDF_RENDERER.render(labyrinth);
+        final Path outputFile = this.targetFile.get();
         try {
-            Files.write(targetFile, bytes);
+            bytes.writeTo(Files.newOutputStream(outputFile));
         } catch (IOException e) {
-            log.error("Failed writing to file " + targetFile.normalize(), e);
+            log.error("Failed writing to file " + outputFile.normalize(), e);
         }
-        return targetFile;
+        return outputFile;
     }
 }