diff --git a/src/blt.c b/src/blt.c
index 381af6e..59549c9 100644
--- a/src/blt.c
+++ b/src/blt.c
@@ -66,6 +66,8 @@ void blt_copy(
                 dst += 128;
                 size -= 128;
             }
+
+            _mm256_zeroupper();
         }
 
         /* memcpy below handles the remainder */