diff --git a/src/gmx/workflow.py b/src/gmx/workflow.py
index 871184228d..0e504f28bd 100644
--- a/src/gmx/workflow.py
+++ b/src/gmx/workflow.py
@@ -397,10 +397,10 @@ def __repr__(self):
 class WorkElement(object):
     """Encapsulate an element of a work specification."""
     def __init__(self, namespace="gmxapi", operation=None, params=None, depends=()):
-        self.namespace = to_string(namespace)
+        self._namespace = str(to_string(namespace))
         # We can add an operations submodule to validate these. E.g. self.operation = gmx.workflow.operations.normalize(operation)
         if operation is not None:
-            self.operation = to_string(operation)
+            self._operation = str(to_string(operation))
         else:
             raise exceptions.UsageError("Invalid argument type for operation.")
 
@@ -423,6 +423,16 @@ def __init__(self, namespace="gmxapi", operation=None, params=None, depends=()):
         self._name = None
         self._workspec = None
 
+    @property
+    def namespace(self):
+        assert isinstance(self._namespace, str)
+        return self._namespace
+
+    @property
+    def operation(self):
+        assert isinstance(self._operation, str)
+        return self._operation
+
     @property
     def name(self):
         assert isinstance(self._name, (str, type(None)))