diff --git a/python/dune/perftool/sumfact/vectorization.py b/python/dune/perftool/sumfact/vectorization.py
index ab5535d71a959185154805c7dd51b40e2baada03..0b023aeb965dde7efbeae4e3f0a6a3b9d1f789e8 100644
--- a/python/dune/perftool/sumfact/vectorization.py
+++ b/python/dune/perftool/sumfact/vectorization.py
@@ -167,7 +167,7 @@ def greedy_vectorization_strategy(sumfacts, width):
                     result[k] = vert[k]
                 sumfacts.discard(sf)
 
-        horizontal = horizontal / 2
+        horizontal = horizontal // 2
         vertical = vertical * 2
 
     return result