modify what is being replaced

oscargus · Nov 22, 2021 · cb4e88d · cb4e88d
1 parent 4905130
commit cb4e88d
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/sympy/concrete/expr_with_limits.py b/sympy/concrete/expr_with_limits.py
@@ -312,8 +312,9 @@ def free_symbols(self):
         # should be returned, e.g. don't return set() if the
         # function is zero -- treat it like an unevaluated expression.
         function, limits = self.function, self.limits
-        # mask off non-symbol integration variables
-        reps = {i[0]: i[0] if isinstance(i[0], Symbol) else Dummy()
+        # mask off non-symbol integration variables that have
+        # more than themself as a free symbol
+        reps = {i[0]: i[0] if i[0].free_symbols == {i[0]} else Dummy()
             for i in self.limits}
         function = function.xreplace(reps)
         isyms = function.free_symbols