diff --git a/patches/base/s3ql/fix-plain-block-size.patch b/patches/base/s3ql/fix-plain-block-size.patch
new file mode 100644
index 0000000..958e099
--- /dev/null
+++ b/patches/base/s3ql/fix-plain-block-size.patch
@@ -0,0 +1,26 @@
+diff --git a/src/s3ql/backends/comprenc.py b/src/s3ql/backends/comprenc.py
+index 6402fec1..9ed3627e 100644
+--- a/src/s3ql/backends/comprenc.py
++++ b/src/s3ql/backends/comprenc.py
+@@ -276,7 +276,7 @@ class ComprencBackend(AbstractBackend):
+             buf.seek(0)
+             fh = buf
+ 
+-        return self.backend.write_fh(key, fh, meta_raw)
++        return self.backend.write_fh(key, fh, meta_raw, len_=len_ if meta_raw['compression'] == 'None'and meta_raw['encryption'] == 'None' else None)
+ 
+     def contains(self, key):
+         return self.backend.contains(key)
+diff --git a/src/s3ql/database.py b/src/s3ql/database.py
+index bb4054e6..c2142bf6 100644
+--- a/src/s3ql/database.py
++++ b/src/s3ql/database.py
+@@ -659,7 +659,7 @@ def upload_metadata(
+             )
+             obj = METADATA_OBJ_NAME % (blockno, params.seq_no)
+             fh.seek(blockno * blocksize)
+-            backend.write_fh(obj, fh, len_=blocksize)
++            backend.write_fh(obj, fh, len_=min(blocksize, db_size - blockno * blocksize))
+ 
+         if not update_params:
+             return