diff --git a/examples/data/mf6/test001a_Tharmonic/flow15.tdis b/examples/data/mf6/test001a_Tharmonic/flow15.tdis
index bccfdc368b..b259bf9ced 100644
--- a/examples/data/mf6/test001a_Tharmonic/flow15.tdis
+++ b/examples/data/mf6/test001a_Tharmonic/flow15.tdis
@@ -9,5 +9,5 @@ BEGIN Dimensions
 END Dimensions
 
 BEGIN PERIODDATA
-   1.00000000               1   1.00000000      Items: PERLEN NSTP TSMULT
+   1.00000000,1,1.00000000      Items: PERLEN NSTP TSMULT
 END PERIODDATA
diff --git a/examples/data/mf6/test001a_Tharmonic/flow15_constant.chd b/examples/data/mf6/test001a_Tharmonic/flow15_constant.chd
index 68bce24d54..56c4b56aa4 100644
--- a/examples/data/mf6/test001a_Tharmonic/flow15_constant.chd
+++ b/examples/data/mf6/test001a_Tharmonic/flow15_constant.chd
@@ -11,6 +11,6 @@ BEGIN Dimensions
 END Dimensions
 
 BEGIN Period 1
-  1  1  1   10.0000000    
+  1  1  1   1D1    
   1  1  10   0.0000000
 END Period
diff --git a/flopy/mf6/data/mfdatautil.py b/flopy/mf6/data/mfdatautil.py
index a1e00ad97c..ab716b6435 100644
--- a/flopy/mf6/data/mfdatautil.py
+++ b/flopy/mf6/data/mfdatautil.py
@@ -78,6 +78,7 @@ def convert_data(data, data_dimensions, data_type, data_item=None, sub_amt=1):
                 if isinstance(data, str):
                     # fix any scientific formatting that python can't handle
                     data = data.replace("d", "e")
+                    data = data.replace("D", "e")
                 return float(data)
             except (ValueError, TypeError):
                 try:
diff --git a/flopy/utils/datautil.py b/flopy/utils/datautil.py
index 8575d7e792..4e594befe1 100644
--- a/flopy/utils/datautil.py
+++ b/flopy/utils/datautil.py
@@ -368,11 +368,21 @@ def split_data_line(line, external_file=False, delimiter_conf_length=15):
                         max_split_type = delimiter
                         max_split_list = alt_split
 
+            if max_split_type is None and max_split_size > 0:
+                split_first = max_split_list[0].strip().split(",")
+                if len(split_first) > 1:
+                    max_split_list = split_first + max_split_list[1:]
+                    max_split_size = len(max_split_list)
+                    max_split_type = "combo"
+
             if max_split_type is not None and max_split_size > 1:
                 clean_line = max_split_list
                 if PyListUtil.line_num == 0:
                     PyListUtil.delimiter_used = max_split_type
-                elif PyListUtil.delimiter_used != max_split_type:
+                elif (
+                    PyListUtil.delimiter_used != max_split_type
+                    or max_split_type == "combo"
+                ):
                     PyListUtil.consistent_delim = False
             if max_split_size > 1:
                 PyListUtil.line_num += 1