--- FIAT/expansions.py.orig	2018-06-14 04:30:19.000000000 -0700
+++ FIAT/expansions.py	2018-08-18 10:49:46.000000000 -0700
@@ -46,7 +46,7 @@
         out = []
         try:
             out = [sympy.diff(F, X[j]) for j in range(D)]
-        except AttributeError:
+        except (AttributeError, ValueError):
             # Intercept errors like
             #  AttributeError: 'list' object has no attribute
             #  'free_symbols'