diff --git a/lix/libexpr/flake/flake.cc b/lix/libexpr/flake/flake.cc
index 94ba34433..9e3711a48 100644
--- a/lix/libexpr/flake/flake.cc
+++ b/lix/libexpr/flake/flake.cc
@@ -1015,6 +1015,7 @@ Value prim_flakeRefToString(EvalState & state, Value ** args)
         "while evaluating the argument passed to builtins.flakeRefToString");
     fetchers::Attrs attrs;
     for (const auto & attr : *args[0]->attrs()) {
+        state.forceValue(attr.value, noPos);
         auto t = attr.value.type();
         if (t == nInt) {
             auto intValue = attr.value.integer().value;
diff --git a/tests/functional2/lang/builtins.flakeRefToString/eval-fail-negative-integer.err.exp b/tests/functional2/lang/builtins.flakeRefToString/eval-fail-negative-integer.err.exp
index fdb4a591a..5e8db03ae 100644
--- a/tests/functional2/lang/builtins.flakeRefToString/eval-fail-negative-integer.err.exp
+++ b/tests/functional2/lang/builtins.flakeRefToString/eval-fail-negative-integer.err.exp
@@ -1,14 +1,9 @@
 error:
-       … while calling the 'seq' builtin
-         at /pwd/in.nix:1:16:
-            1| let n = -1; in builtins.seq n (builtins.flakeRefToString {
-             |                ^
-            2|   type  = "github";
-
        … while calling the 'flakeRefToString' builtin
-         at /pwd/in.nix:1:32:
-            1| let n = -1; in builtins.seq n (builtins.flakeRefToString {
-             |                                ^
-            2|   type  = "github";
+         at /pwd/in.nix:4:1:
+            3| in
+            4| builtins.flakeRefToString {
+             | ^
+            5|   type  = "github";
 
        error: negative value given for flake ref attr repo: -1
diff --git a/tests/functional2/lang/builtins.flakeRefToString/in-negative-integer.nix b/tests/functional2/lang/builtins.flakeRefToString/in-negative-integer.nix
index e0208eb25..790f138ca 100644
--- a/tests/functional2/lang/builtins.flakeRefToString/in-negative-integer.nix
+++ b/tests/functional2/lang/builtins.flakeRefToString/in-negative-integer.nix
@@ -1,7 +1,10 @@
-let n = -1; in builtins.seq n (builtins.flakeRefToString {
+let
+  n = -1;
+in
+builtins.flakeRefToString {
   type  = "github";
   owner = "NixOS";
   repo  = n;
   ref   = "23.05";
   dir   = "lib";
-})
+}