diff --git a/galvani/BioLogic.py b/galvani/BioLogic.py
index 1758ab5..0a0db5f 100644
--- a/galvani/BioLogic.py
+++ b/galvani/BioLogic.py
@@ -238,7 +238,7 @@ def VMPdata_dtype_from_colIDs(colIDs):
             type_list.append((unique_field_name, field_type))
         else:
             raise NotImplementedError("Column ID {cid} after column {prev} "
-                "is unknown".format(cid=colID, prev=type_list[-1][0]))
+                    "is unknown".format(cid=colID, prev=type_list[-1][0]))
     return np.dtype(type_list), flags_dict