diff --git a/src/calibre/gui2/viewer/annotations.py b/src/calibre/gui2/viewer/annotations.py
index 16a1cf6476..81ce8c9904 100644
--- a/src/calibre/gui2/viewer/annotations.py
+++ b/src/calibre/gui2/viewer/annotations.py
@@ -59,11 +59,18 @@ def serialize_annotations(annots_map):
     return json_dumps(ans)
 
 
+def split_lines(chunk, length=80):
+    pos = 0
+    while pos < len(chunk):
+        yield chunk[pos:pos+length]
+        pos += length
+
+
 def save_annots_to_epub(path, serialized_annots):
     try:
         zf = open(path, 'r+b')
     except IOError:
         return
     with zf:
-        serialized_annots = EPUB_FILE_TYPE_MAGIC + as_base64_bytes(serialized_annots)
+        serialized_annots = EPUB_FILE_TYPE_MAGIC + b'\n'.join(split_lines(as_base64_bytes(serialized_annots)))
         safe_replace(zf, 'META-INF/calibre_bookmarks.txt', BytesIO(serialized_annots), add_missing=True)
diff --git a/src/calibre/srv/render_book.py b/src/calibre/srv/render_book.py
index 5fe91dff16..1cb34c89c3 100644
--- a/src/calibre/srv/render_book.py
+++ b/src/calibre/srv/render_book.py
@@ -560,15 +560,16 @@ def parse_annotations(raw):
 
 
 def get_stored_annotations(container):
-    from calibre.ebooks.oeb.iterator.bookmarks import parse_bookmarks
-
     raw = container.bookmark_data or b''
+    if not raw:
+        return
     if raw.startswith(EPUB_FILE_TYPE_MAGIC):
-        raw = raw[len(EPUB_FILE_TYPE_MAGIC):]
+        raw = raw[len(EPUB_FILE_TYPE_MAGIC):].replace(b'\n', b'')
         for annot in parse_annotations(from_base64_bytes(raw)):
             yield annot
         return
 
+    from calibre.ebooks.oeb.iterator.bookmarks import parse_bookmarks
     for bm in parse_bookmarks(raw):
         if bm['type'] == 'cfi' and isinstance(bm['pos'], unicode_type):
             spine_index = (1 + bm['spine']) * 2