diff --git a/tests/packages.scm b/tests/packages.scm
index 65e5cc3cdd..851520b343 100644
--- a/tests/packages.scm
+++ b/tests/packages.scm
@@ -270,14 +270,15 @@
 
 (test-assert "reference to non-existent output"
   ;; See <http://bugs.gnu.org/19630>.
-  (let* ((dep (dummy-package "dep"))
-         (p   (dummy-package "p"
-                (inputs `(("dep" ,dep "non-existent"))))))
-    (guard (c ((derivation-missing-output-error? c)
-               (and (string=? (derivation-missing-output c) "non-existent")
-                    (equal? (package-derivation %store dep)
-                            (derivation-error-derivation c)))))
-      (package-derivation %store p))))
+  (parameterize ((%graft? #f))
+    (let* ((dep (dummy-package "dep"))
+           (p   (dummy-package "p"
+                  (inputs `(("dep" ,dep "non-existent"))))))
+      (guard (c ((derivation-missing-output-error? c)
+                 (and (string=? (derivation-missing-output c) "non-existent")
+                      (equal? (package-derivation %store dep)
+                              (derivation-error-derivation c)))))
+        (package-derivation %store p)))))
 
 (test-assert "trivial"
   (let* ((p (package (inherit (dummy-package "trivial"))