diff --git a/src/cell.h b/src/cell.h
index b223c839a03dac12829e853bad47deda1eb3d1f7..984ef4bc20cf07285b136461815cd0851c12291a 100644
--- a/src/cell.h
+++ b/src/cell.h
@@ -56,7 +56,7 @@ extern int cell_next_tag;
 struct cell_buff {
   double x[3];
   int ind;
-};
+} SWIFT_STRUCT_ALIGN;
 
 /* Mini struct to link cells to tasks. Used as a linked list. */
 struct link {