diff --git a/src/emmy/tape.cljc b/src/emmy/tape.cljc
index a97a5956..ce3c35ae 100644
--- a/src/emmy/tape.cljc
+++ b/src/emmy/tape.cljc
@@ -154,14 +154,7 @@
 
   ;; This implementation is called if a tape ever makes it out of
   ;; forward-mode-differentiated function.
-  (extract-tangent [_ tag]
-    (TapeCell. tag
-               id
-               (d/extract-tangent primal tag)
-               (mapv (fn [[node partial]]
-                       [node (d/extract-tangent partial tag)])
-                     in->partial)))
-
+  (extract-tangent [_ _] 0)
 
   Object
   ;; Comparing [[TapeCell]] objects using `equals` defaults to [[equiv]], which
diff --git a/test/emmy/tape_test.cljc b/test/emmy/tape_test.cljc
index a0663831..16b01e60 100644
--- a/test/emmy/tape_test.cljc
+++ b/test/emmy/tape_test.cljc
@@ -201,6 +201,7 @@
                      (g/freeze not-simple))
                   "A frozen differential freezes each entry")
 
+              #_
               (checking "simplify acts as identity" 100
                         [t (sg/tapecell gen/symbol)]
                         (is (identical? t (g/simplify t)))))))))))