diff --git a/lib/spack/spack/environment.py b/lib/spack/spack/environment.py
index 151e73a0fd9..efc43b0250d 100644
--- a/lib/spack/spack/environment.py
+++ b/lib/spack/spack/environment.py
@@ -933,6 +933,7 @@ def remove(self, query_spec, list_name=user_speclist_name, force=False):
                 "Not found: {0}".format(query_spec))
 
         old_specs = set(self.user_specs)
+        new_specs = set()
         for spec in matches:
             if spec in list_to_change:
                 try: