diff --git a/python/sdist/amici/sbml_import.py b/python/sdist/amici/sbml_import.py
index d14692a1f1..0294180237 100644
--- a/python/sdist/amici/sbml_import.py
+++ b/python/sdist/amici/sbml_import.py
@@ -3066,7 +3066,7 @@ def is_assignment_rule_target(self, element: libsbml.SBase) -> bool:
             boolean indicating truth of function name
         """
         a = self.sbml.getAssignmentRuleByVariable(element.getId())
-        return a is not None and self._sympify(a) is not None
+        return a is not None and a.getMath() is not None
 
     def is_rate_rule_target(self, element: libsbml.SBase) -> bool:
         """
@@ -3080,7 +3080,7 @@ def is_rate_rule_target(self, element: libsbml.SBase) -> bool:
             boolean indicating truth of function name
         """
         a = self.sbml.getRateRuleByVariable(element.getId())
-        return a is not None and self._sympify(a) is not None
+        return a is not None and a.getMath() is not None
 
     def _transform_dxdt_to_concentration(
         self, species_id: sp.Symbol, dxdt: sp.Expr
diff --git a/python/sdist/pyproject.toml b/python/sdist/pyproject.toml
index 2592e38f8f..228fa76ac5 100644
--- a/python/sdist/pyproject.toml
+++ b/python/sdist/pyproject.toml
@@ -65,7 +65,8 @@ test = [
     "h5py",
     "pytest",
     "pytest-cov",
-    "pytest-rerunfailures",
+    # v16.0: https://github.com/pytest-dev/pytest-rerunfailures/issues/302
+    "pytest-rerunfailures!=16.0",
     "coverage",
     "shyaml",
     "antimony>=2.13",