diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 119e71a04..422ec971c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -796,7 +796,7 @@ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Val
     for (auto & ent : entries) {
         Value * ent_val = state.allocAttr(v, state.symbols.create(ent.name));
         if (ent.type == DT_UNKNOWN)
-            ent.type = getFileType(path);
+            ent.type = getFileType(path + "/" + ent.name);
         mkStringNoCopy(*ent_val,
             ent.type == DT_REG ? "regular" :
             ent.type == DT_DIR ? "directory" :