diff --git a/kwant/continuum/_common.py b/kwant/continuum/_common.py
index 6715c690046f402e43234a5a6fc6af4b5a14c039..9b14ef129bb4ae8a12dbf8c80ba5de883e370841 100644
--- a/kwant/continuum/_common.py
+++ b/kwant/continuum/_common.py
@@ -183,7 +183,7 @@ def sympify(expr, locals=None):
             converter[list] = stored_value
         else:
             del converter[list]
-    return sympy.expand(hamiltonian)
+    return hamiltonian
 
 
 def make_commutative(expr, *symbols):
diff --git a/kwant/continuum/discretizer.py b/kwant/continuum/discretizer.py
index 7eba3855dfc477567f8483798e827ff9877c741b..44788ecd6031a5095b7282c47f5c5467cc1a6c05 100644
--- a/kwant/continuum/discretizer.py
+++ b/kwant/continuum/discretizer.py
@@ -370,7 +370,7 @@ def _discretize_summand(summand, coords):
         else:
             result = factor * result
 
-    return sympy.expand(result)
+    return result
 
 
 def _discretize_expression(expression, coords):