diff --git a/flopy/mf6/data/mffileaccess.py b/flopy/mf6/data/mffileaccess.py
index 653f54a29b..bfadbde27d 100644
--- a/flopy/mf6/data/mffileaccess.py
+++ b/flopy/mf6/data/mffileaccess.py
@@ -215,6 +215,7 @@ def write_binary_file(
         if data.size == modelgrid.nnodes:
             write_multi_layer = False
         if write_multi_layer:
+            # write data from each layer with a separate header
             for layer, value in enumerate(data):
                 self._write_layer(
                     fd,
@@ -228,6 +229,7 @@ def write_binary_file(
                     layer + 1,
                 )
         else:
+            # write data with a single header
             self._write_layer(
                 fd,
                 data,
@@ -238,7 +240,6 @@ def write_binary_file(
                 text,
                 fname,
             )
-        data.tofile(fd)
         fd.close()
 
     def _write_layer(