diff --git a/python/sdist/amici/de_export.py b/python/sdist/amici/de_export.py
index 53d59ad4e9..e7aa3fd146 100644
--- a/python/sdist/amici/de_export.py
+++ b/python/sdist/amici/de_export.py
@@ -1663,7 +1663,7 @@ def static_indices(self, name: str) -> list[int]:
                         not self._splines or "AmiciSpline" not in str(expr)
                     )
                     and (
-                        not expr.has(dynamic_syms)
+                        not expr.has(*dynamic_syms)
                         or all(
                             expr.diff(dyn_sym).is_zero
                             for dyn_sym in dynamic_syms