diff --git a/gnu/packages/chromium.scm b/gnu/packages/chromium.scm
index 54067e5c11..470936bea7 100644
--- a/gnu/packages/chromium.scm
+++ b/gnu/packages/chromium.scm
@@ -220,6 +220,7 @@ (define* (computed-origin-method gexp-promise hash-algo hash
   (mlet %store-monad ((guile (package->derivation guile system)))
     (gexp->derivation (or name "computed-origin")
                       (force gexp-promise)
+                      #:graft? #f       ;nothing to graft
                       #:system system
                       #:guile-for-build guile)))
 
diff --git a/gnu/packages/gnuzilla.scm b/gnu/packages/gnuzilla.scm
index 0bb3df0f73..74e5458430 100644
--- a/gnu/packages/gnuzilla.scm
+++ b/gnu/packages/gnuzilla.scm
@@ -573,6 +573,7 @@ (define* (computed-origin-method gexp-promise hash-algo hash
   (mlet %store-monad ((guile (package->derivation guile system)))
     (gexp->derivation (or name "computed-origin")
                       (force gexp-promise)
+                      #:graft? #f       ;nothing to graft
                       #:system system
                       #:guile-for-build guile)))