diff --git a/common/python/nomadcore/md_data_access/MDDataAccess.py b/common/python/nomadcore/md_data_access/MDDataAccess.py
index 154a2cf210e31d617ea5ce6529e209999fbd4adb..f31056e50c87c6c226f541051f19ea2f3ea9cf32 100644
--- a/common/python/nomadcore/md_data_access/MDDataAccess.py
+++ b/common/python/nomadcore/md_data_access/MDDataAccess.py
@@ -2406,7 +2406,7 @@ class MDDataAccess(object):
             chkfilename = os.path.basename(chkfile)
         if chkformat is None:
             fileloadformat = self.get_file_format(chkfile, chkformat)
-            chkformat = file_format
+            chkformat = fileloadformat
             if "input" in filetype:
                 self.incoordformat = fileloadformat
             elif "output" in filetype: