diff --git a/src/main/java/de/thm/arsnova/ImageUtils.java b/src/main/java/de/thm/arsnova/ImageUtils.java
index b72c9262138d8a843c79eff747b8dbe9378e996b..5acb8866838916e38b67771335f1575336e4529f 100644
--- a/src/main/java/de/thm/arsnova/ImageUtils.java
+++ b/src/main/java/de/thm/arsnova/ImageUtils.java
@@ -175,7 +175,7 @@ public class ImageUtils {
 			final String[] imgInfo = extractImageInfo(originalImageString);
 
 			// imgInfo isn't null and contains two fields, this is checked by "isBase64EncodedImage"-Method
-			final String extension = imgInfo[0];
+			final String extension = "png";
 			final String base64String = imgInfo[1];
 
 			byte[] imageData = Base64.decodeBase64(base64String);