diff --git a/pdb-plotting/src/main/java/org/lucares/recommind/logs/ScatterPlot.java b/pdb-plotting/src/main/java/org/lucares/recommind/logs/ScatterPlot.java
index 8383987..82fc533 100644
--- a/pdb-plotting/src/main/java/org/lucares/recommind/logs/ScatterPlot.java
+++ b/pdb-plotting/src/main/java/org/lucares/recommind/logs/ScatterPlot.java
@@ -110,7 +110,7 @@ public class ScatterPlot implements ConcretePlotter {
 			DataSeries.sortAndLimit(dataSeries, limitBy, limit);
 			DataSeries.setColors(dataSeries);
 
-			final Path outputFile = Files.createTempFile(outputDir, "out", ".png");
+			final Path outputFile = Files.createTempFile(outputDir, "", ".png");
 			final Gnuplot gnuplot = new Gnuplot(tmpBaseDir);
 			final GnuplotSettings gnuplotSettings = new GnuplotSettings(outputFile);
 			gnuplotSettings.setHeight(height);
@@ -158,10 +158,9 @@ public class ScatterPlot implements ConcretePlotter {
 				final BufferedImage image = ImageIO.read(originalImage.toFile());
 
 				final BufferedImage thumbnail = resizeImage(image, thumbnailMaxWidth, thumbnailMaxHeight);
-				final Path thumbnailPath = originalImage.getParent()
-						.resolve(originalImage.getFileName() + ".thumbnail.jpg");
+				final Path thumbnailPath = Files.createTempFile(outputDir, "", ".png");
 
-				ImageIO.write(thumbnail, "JPG", thumbnailPath.toFile());
+				ImageIO.write(thumbnail, "png", thumbnailPath.toFile());
 				LOGGER.info("thumbnail creation: " + (System.nanoTime() - start) / 1_000_000.0 + "ms");
 				result = thumbnailPath;
 			} catch (final IOException | RuntimeException e) {