diff --git a/src/dewret/workflow.py b/src/dewret/workflow.py
index 30268d91..38b0a6b1 100644
--- a/src/dewret/workflow.py
+++ b/src/dewret/workflow.py
@@ -23,11 +23,11 @@
 from attrs import has as attr_has, resolve_types, fields as attrs_fields
 from dataclasses import is_dataclass, fields as dataclass_fields
 from collections import Counter, OrderedDict
-from typing import Protocol, Any, TypeVar, Generic, cast, Literal, Iterable, get_origin, get_args, Generator, Sized, Sequence, get_type_hints, TYPE_CHECKING
+from typing import Protocol, Any, TypeVar, Generic, cast, Literal, Iterable, get_origin, get_args, Generator, Sized, Sequence, get_type_hints, TYPE_CHECKING, Hashable
 from uuid import uuid4
 import logging
 
-from sympy import Symbol, Expr, Basic
+from sympy import Symbol, Expr, Basic, Tuple
 
 logger = logging.getLogger(__name__)
 
@@ -545,12 +545,24 @@ def assimilate(cls, *workflow_args: Workflow) -> "Workflow":
         for step in base.steps:
             step.set_workflow(base, with_arguments=True)
 
-        results = sorted(set((w.result for w in workflows if w.has_result)))
+        hashable_workflows: list[Workflow] = [w for w in workflows if isinstance(w.result, Hashable)]
+        if len(hashable_workflows) != len(workflows):
+            raise NotImplementedError("Some results are not hashable.")
+
+        def _get_order(result: None | StepReference | Iterable[StepReference]) -> str:
+            if result is None:
+                return ""
+            if isinstance(result, StepReference):
+                return result.id
+            return "|".join(r for r in result)
+
+
+        results = sorted(set({w.result for w in hashable_workflows if w.has_result}), key=lambda r: _get_order(r))
         if len(results) == 1:
             result = results[0]
         else:
-            results = sorted({r if isinstance(r, tuple | list) else (r,) for r in results})
-            result = sum(map(list, results), [])
+            list_results = [r if isinstance(r, tuple | list | Tuple) else (r,) for r in results]
+            result = sum(map(list, list_results), [])
 
         if result is not None and result != []:
             unify_workflows(result, base, set_only=True)