diff --git a/pgxn/hnsw/hnsw.c b/pgxn/hnsw/hnsw.c
index 45bf78ed3b..9849a69283 100644
--- a/pgxn/hnsw/hnsw.c
+++ b/pgxn/hnsw/hnsw.c
@@ -580,6 +580,7 @@ l2_distance(PG_FUNCTION_ARGS)
 				 errmsg("different array dimensions %d and %d", a_dim, b_dim)));
 	}
 
+	#pragma clang loop vectorize(enable)
 	for (int i = 0; i < a_dim; i++)
 	{
 		diff = ax[i] - bx[i];