diff --git a/cdist/exec/util.py b/cdist/exec/util.py
index 9787f431..e3be2235 100644
--- a/cdist/exec/util.py
+++ b/cdist/exec/util.py
@@ -199,7 +199,9 @@ def resolve_conf_dirs(configuration, add_conf_dirs):
 
     if add_conf_dirs:
         conf_dirs.extend(add_conf_dirs)
-    conf_dirs = set(conf_dirs)
+
+    # Remove duplicates.
+    conf_dirs = list(dict.fromkeys(conf_dirs))
     return conf_dirs