diff --git a/loopy/transform/diff.py b/loopy/transform/diff.py
index 0d80ee99ccbe5611fc7169884e240342f3065525..1f75a60b877d9ddad416688180aa082c134618bf 100644
--- a/loopy/transform/diff.py
+++ b/loopy/transform/diff.py
@@ -296,10 +296,9 @@ class DifferentiationContext(object):
             return None
 
         assert isinstance(orig_writer_insn, lp.Assignment)
-        from pymbolic import Variable, Subscript
-        if isinstance(orig_writer_insn.assignee, Subscript):
+        if isinstance(orig_writer_insn.assignee, p.Subscript):
             lhs_ind = orig_writer_insn.assignee.index_tuple
-        elif isinstance(orig_writer_insn.assignee, Variable):
+        elif isinstance(orig_writer_insn.assignee, p.Variable):
             lhs_ind = ()
         else:
             raise LoopyError(
diff --git a/loopy/transform/subst.py b/loopy/transform/subst.py
index 6cbf43da3fb4a3484ba028c96a2c0151e0582658..27e98383ee7211643aecdafebc9bf63988c55e0c 100644
--- a/loopy/transform/subst.py
+++ b/loopy/transform/subst.py
@@ -394,7 +394,7 @@ def assignment_to_subst(kernel, lhs_name, extra_arguments=(), within=None,
         from loopy.kernel.data import Assignment
         assert isinstance(def_insn, Assignment)
 
-        from pymbolic import Variable, Subscript
+        from pymbolic.primitives import Variable, Subscript
         if isinstance(def_insn.assignee, Subscript):
             indices = def_insn.assignee.index_tuple
         elif isinstance(def_insn.assignee, Variable):