diff --git a/jaraco/test/services.py b/jaraco/test/services.py
index <HASH>..<HASH> 100644
--- a/jaraco/test/services.py
+++ b/jaraco/test/services.py
@@ -328,7 +328,7 @@ class MongoDBFinder(paths.PathFinder):
     #  be found.
     env_paths = [
         os.path.join(os.environ[key], 'bin')
-        for key in 'MONGODB_HOME'
+        for key in ['MONGODB_HOME']
         if key in os.environ
     ]
     candidate_paths = env_paths or heuristic_paths
Replace string constant with a list containing the string

Previously, the list comprehension would iterate over the
characters in the string, which is not the desired behavior.

--HG--
branch : fix-mongodbfinder