1 files changed, 3 insertions, 1 deletions
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index bcc7736ac..78692b9c6 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -105,8 +105,10 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
     /* Also write a copy of the list of user environment elements to
        the store; we need it for future modifications of the
        environment. */
+    std::ostringstream str;
+    manifest.print(str, true);
     auto manifestFile = state.store->addTextToStore("env-manifest.nix",
-        fmt("%s", manifest), references);
+        str.str(), references);
 
     /* Get the environment builder expression. */
     Value envBuilder;