diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index 9693f1773..33301933c 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -228,6 +228,9 @@ void Input::checkLocks(Input specified, Input & result)
         if (auto prevNarHash = specified.getNarHash())
             specified.attrs.insert_or_assign("narHash", prevNarHash->to_string(HashFormat::SRI, true));
 
+        if (auto narHash = result.getNarHash())
+            result.attrs.insert_or_assign("narHash", narHash->to_string(HashFormat::SRI, true));
+
         for (auto & field : specified.attrs) {
             auto field2 = result.attrs.find(field.first);
             if (field2 != result.attrs.end() && field.second != field2->second)