diff --git a/mayan/apps/converter/classes.py b/mayan/apps/converter/classes.py
index 1c25b36241..a7024ebdc3 100644
--- a/mayan/apps/converter/classes.py
+++ b/mayan/apps/converter/classes.py
@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+import base64
 import logging
 import os
 import tempfile
@@ -168,7 +169,7 @@ class ConverterBase(object):
 
         fs_cleanup(input_filepath)
 
-    def get_page(self, output_format=DEFAULT_FILE_FORMAT):
+    def get_page(self, output_format=DEFAULT_FILE_FORMAT, as_base64=False):
         if not self.image:
             self.seek(0)
 
@@ -183,9 +184,13 @@ class ConverterBase(object):
                     new_mode = 'RGBA'
 
         self.image.convert(new_mode).save(image_buffer, format=output_format)
-        image_buffer.seek(0)
 
-        return image_buffer
+        if as_base64:
+            return 'data:{};base64,{}'.format(Image.MIME[output_format], base64.b64encode(image_buffer.getvalue()))
+        else:
+            image_buffer.seek(0)
+
+            return image_buffer
 
     def convert(self, page_number=DEFAULT_PAGE_NUMBER):
         self.page_number = page_number
diff --git a/mayan/apps/converter/literals.py b/mayan/apps/converter/literals.py
index 2377661029..e058f313bc 100644
--- a/mayan/apps/converter/literals.py
+++ b/mayan/apps/converter/literals.py
@@ -3,7 +3,6 @@ from __future__ import unicode_literals
 DEFAULT_ZOOM_LEVEL = 100
 DEFAULT_ROTATION = 0
 DEFAULT_PAGE_NUMBER = 1
-DEFAULT_FILE_FORMAT = 'jpeg'
-DEFAULT_FILE_FORMAT_MIMETYPE = 'image/jpeg'
+DEFAULT_FILE_FORMAT = 'JPEG'
 
 DIMENSION_SEPARATOR = 'x'
diff --git a/mayan/apps/documents/models.py b/mayan/apps/documents/models.py
index 24ea112b21..74e1a7b76a 100644
--- a/mayan/apps/documents/models.py
+++ b/mayan/apps/documents/models.py
@@ -753,15 +753,7 @@ class DocumentPage(models.Model):
                 transformation=TransformationZoom(percent=zoom_level)
             )
 
-        page_image = converter.get_page()
-
-        if as_base64:
-            # TODO: don't prepend 'data:%s;base64,%s' part
-            return 'data:%s;base64,%s' % (
-                'image/png', base64.b64encode(page_image.getvalue())
-            )
-        else:
-            return page_image
+        return converter.get_page(as_base64=as_base64)
 
     def invalidate_cache(self):
         cache_storage_backend.delete(self.cache_filename)
diff --git a/mayan/apps/documents/serializers.py b/mayan/apps/documents/serializers.py
index 911d878a5e..8a07cb12d4 100644
--- a/mayan/apps/documents/serializers.py
+++ b/mayan/apps/documents/serializers.py
@@ -27,8 +27,6 @@ class DocumentPageImageSerializer(serializers.Serializer):
                 rotation=rotation, as_base64=True
             )
         )
-        # TODO: prepend 'data:%s;base64,%s' based on format specified in
-        # async call
         return task.get(timeout=DOCUMENT_IMAGE_TASK_TIMEOUT)
 
 
diff --git a/mayan/apps/documents/views.py b/mayan/apps/documents/views.py
index 74f3858bf9..ccdb4bf997 100644
--- a/mayan/apps/documents/views.py
+++ b/mayan/apps/documents/views.py
@@ -729,7 +729,7 @@ def get_document_image(request, document_id, size=setting_preview_size.value):
 
     task = task_get_document_page_image.apply_async(kwargs=dict(document_page_id=document_page.pk, size=size, zoom=zoom, rotation=rotation, as_base64=True, version=version))
     data = task.get(timeout=DOCUMENT_IMAGE_TASK_TIMEOUT)
-    return HttpResponse(base64.b64decode(data[21:]), content_type='image')
+    return HttpResponse(base64.b64decode(data[data.find('base64,') + 6:]), content_type='image')
 
 
 def document_download(request, document_id=None, document_id_list=None, document_version_pk=None):
diff --git a/mayan/apps/sources/classes.py b/mayan/apps/sources/classes.py
index 9b8aa3b0c5..e53fdb6399 100644
--- a/mayan/apps/sources/classes.py
+++ b/mayan/apps/sources/classes.py
@@ -85,13 +85,7 @@ class StagingFile(object):
         for transformation in transformations:
             converter.transform(transformation=transformation)
 
-        image_data = converter.get_page()
-
-        if as_base64:
-            base64_data = base64.b64encode(image_data.read())
-            return 'data:%s;base64,%s' % ('image/png', base64_data)
-        else:
-            return image_data
+        return converter.get_page(as_base64=as_base64)
 
     def delete(self):
         os.unlink(self.get_full_path())