diff --git a/pyiron_workflow/workflow.py b/pyiron_workflow/workflow.py
index 8b0a707bd..24c2032b2 100644
--- a/pyiron_workflow/workflow.py
+++ b/pyiron_workflow/workflow.py
@@ -225,10 +225,8 @@ def __init__(
         automate_execution: bool = True,
         **kwargs,
     ):
-        self._inputs_map = None
-        self._outputs_map = None
-        self.inputs_map = inputs_map
-        self.outputs_map = outputs_map
+        self._inputs_map = self._sanitize_map(inputs_map)
+        self._outputs_map = self._sanitize_map(outputs_map)
         self._inputs = None
         self._outputs = None
         self.automate_execution: bool = automate_execution
@@ -264,34 +262,36 @@ def _after_node_setup(
 
     @property
     def inputs_map(self) -> bidict | None:
-        self._deduplicate_nones(self._inputs_map)
+        if self._inputs_map is not None:
+            self._deduplicate_nones(self._inputs_map)
         return self._inputs_map
 
     @inputs_map.setter
     def inputs_map(self, new_map: dict | bidict | None):
-        self._deduplicate_nones(new_map)
-        if new_map is not None:
-            new_map = bidict(new_map)
-        self._inputs_map = new_map
+        self._inputs_map = self._sanitize_map(new_map)
 
     @property
     def outputs_map(self) -> bidict | None:
-        self._deduplicate_nones(self._outputs_map)
+        if self._outputs_map is not None:
+            self._deduplicate_nones(self._outputs_map)
         return self._outputs_map
 
     @outputs_map.setter
     def outputs_map(self, new_map: dict | bidict | None):
-        self._deduplicate_nones(new_map)
+        self._outputs_map = self._sanitize_map(new_map)
+
+    def _sanitize_map(self, new_map: dict | bidict | None) -> bidict | None:
         if new_map is not None:
+            if isinstance(new_map, dict):
+                self._deduplicate_nones(new_map)
             new_map = bidict(new_map)
-        self._outputs_map = new_map
+        return new_map
 
     @staticmethod
-    def _deduplicate_nones(some_map: dict | bidict | None) -> dict | bidict | None:
-        if some_map is not None:
-            for k, v in some_map.items():
-                if v is None:
-                    some_map[k] = (None, f"{k} disabled")
+    def _deduplicate_nones(some_map: dict | bidict):
+        for k, v in some_map.items():
+            if v is None:
+                some_map[k] = (None, f"{k} disabled")
 
     @property
     def inputs(self) -> Inputs: