diff --git a/swash/processing/swash.py b/swash/processing/swash.py
index bcf9244..aa36c31 100644
--- a/swash/processing/swash.py
+++ b/swash/processing/swash.py
@@ -29,7 +29,7 @@ with tempfile.TemporaryDirectory(prefix="swash_", dir=".") as tmp_raw:
     tmpdir = pathlib.Path(tmp_raw)
 
     if config.has_option("swash", "mpi"):
-        mpi = ("-mpi", config.getint("swash", "mpi"))
+        mpi = ("-mpi", config.get("swash", "mpi"))
     else:
         mpi = ()