diff --git a/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.exp b/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.exp
index a136b0035..e27068dac 100644
--- a/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.exp
+++ b/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.exp
@@ -1 +1 @@
-[ true true true true true true true true true true true true true ]
+[ true true true true true true true true true true true true true true ]
diff --git a/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.nix b/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.nix
index e5719e00c..3fe8b4cbb 100644
--- a/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.nix
+++ b/tvix/glue/src/tests/tvix_tests/eval-okay-context-introspection.nix
@@ -80,4 +80,5 @@ in
   # `toJSON` tests
   (builtins.hasContext (builtins.toJSON an-str))
   (builtins.hasContext (builtins.toJSON an-list))
+  (builtins.hasContext (builtins.toJSON { __toString = _: "${drv}"; }))
 ]