diff --git a/pymbolic/mapper/__init__.py b/pymbolic/mapper/__init__.py
index 1c1f65e126f36fa1dcdb869fae7ec12625fe8e26..8970a743c990895d643c961e8f72b20cf63cd0d9 100644
--- a/pymbolic/mapper/__init__.py
+++ b/pymbolic/mapper/__init__.py
@@ -284,7 +284,9 @@ class CombineMapper(RecursiveMapper):
         return self.combine(self.rec(el) for el in expr.flat)
 
     def map_multivector(self, expr, *args, **kwargs):
-        return self.combine(self.rec(coeff) for bits, coeff in six.iteritems(expr.data))
+        return self.combine(
+                self.rec(coeff)
+                for bits, coeff in six.iteritems(expr.data))
 
     def map_common_subexpression(self, expr, *args, **kwargs):
         return self.rec(expr.child, *args, **kwargs)