diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 0a0f9a19289..700ae569368 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -59,7 +59,7 @@
 import re
 import socket
 import warnings
-from typing import Any, Callable, Dict, List, Match, Optional, Set, Tuple, Union
+from typing import Any, Callable, Dict, Iterable, List, Match, Optional, Set, Tuple, Union
 
 import archspec.cpu