diff --git a/src/mdevaluate/checksum.py b/src/mdevaluate/checksum.py
index 8a234eb..f651987 100755
--- a/src/mdevaluate/checksum.py
+++ b/src/mdevaluate/checksum.py
@@ -73,7 +73,9 @@ def checksum(*args, csum=None):
         elif isinstance(arg, FunctionType):
             csum.update(strip_comments(inspect.getsource(arg)).encode())
             c = inspect.getclosurevars(arg)
-            for v in {**c.nonlocals, **c.globals}.values():
+            merged = {**c.nonlocals, **c.globals}
+            for key in sorted(merged):  # deterministic ordering
+                v = merged[key]
                 if v is not arg:
                     checksum(v, csum=csum)
         elif isinstance(arg, functools.partial):