diff --git a/pylogix/eip.py b/pylogix/eip.py
index de3040a..3ae5805 100644
--- a/pylogix/eip.py
+++ b/pylogix/eip.py
@@ -511,10 +511,16 @@ def _multiWrite(self, write_data):
                 typ = type(wd[1])
                 value = typ(wd[1])
 
+            # ensure that write values are always a list
+            if isinstance(value, (list, tuple)):
+                value = value
+            else:
+                value = [value]
+
             if BitofWord(tag_name) or data_type == 0xd3:
-                write_service = self._add_mod_write_service(tag_name, ioi, [value], data_type)
+                write_service = self._add_mod_write_service(tag_name, ioi, value, data_type)
             else:
-                write_service = self._add_write_service(ioi, [value], data_type)
+                write_service = self._add_write_service(ioi, value, data_type)
 
             serviceSegments.append(write_service)
 
diff --git a/tox.ini b/tox.ini
index db50f1d..2100e93 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py27, py34, py35, py37
+envlist = py27, py34, py35, py37, py38
 
 [testenv]
 deps =