diff --git a/read-tree.nix b/read-tree.nix
index b2f161e88..2e182dfbd 100644
--- a/read-tree.nix
+++ b/read-tree.nix
@@ -72,10 +72,12 @@ let
     in listToAttrs (imported ++ dirs);
 
   importOr = path: dir: f:
-    let contents = f path (attrsToList dir);
+    let
+      allContents = f path (attrsToList dir);
+      dirOnlyContents = f path (filter (f: f.value == "directory") (attrsToList dir));
     in if dir ? "default.nix"
-      then import path (argsWithPath args (pathParts path)) // contents
-      else contents;
+      then import path (argsWithPath args (pathParts path)) // dirOnlyContents
+      else allContents;
 
   readTree = path: importOr path (readDir path) traverse;
 in readTree initPath