diff --git a/psims/mzmlb/writer.py b/psims/mzmlb/writer.py
index a96c32b..d2f39c3 100644
--- a/psims/mzmlb/writer.py
+++ b/psims/mzmlb/writer.py
@@ -57,7 +57,7 @@
 
 HDF5_COMPRESSORS = {}
 
-DEFAULT_COMPRESSOR = 'gzip'
+DEFAULT_COMPRESSOR = 'zlib:9'
 
 if hdf5plugin is not None:
     HDF5_COMPRESSORS = {