diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index dbe6dff892f..50161db563b 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -153,6 +153,7 @@
     r"|"
     # OPTION 3: mismatched close brace (option 2 would consume a matched open brace)
     r"(})" r")",  # brace
+    r")",
     re.IGNORECASE,
 )