diff --git a/src/core/crypto/relay_crypto.c b/src/core/crypto/relay_crypto.c
index 0b83b2d0a5..d4116d47ab 100644
--- a/src/core/crypto/relay_crypto.c
+++ b/src/core/crypto/relay_crypto.c
@@ -142,6 +142,13 @@ relay_decrypt_cell(circuit_t *circ, cell_t *cell,
           if (relay_digest_matches(thishop->crypto.b_digest, cell)) {
             *recognized = 1;
             *layer_hint = thishop;
+            /* Keep current digest of this cell for the possible SENDME. */
+            if (thishop->crypto.sendme_digest) {
+              crypto_digest_free(thishop->crypto.sendme_digest);
+            }
+            thishop->crypto.sendme_digest =
+              crypto_digest_dup(thishop->crypto.b_digest);
+
             return 0;
           }
         }
@@ -212,6 +219,11 @@ relay_encrypt_cell_inbound(cell_t *cell,
                            or_circuit_t *or_circ)
 {
   relay_set_digest(or_circ->crypto.b_digest, cell);
+  /* Keep a record of this cell, we might use it for validating the SENDME. */
+  if (or_circ->crypto.sendme_digest) {
+    crypto_digest_free(or_circ->crypto.sendme_digest);
+  }
+  or_circ->crypto.sendme_digest = crypto_digest_dup(or_circ->crypto.b_digest);
   /* encrypt one layer */
   relay_crypt_one_payload(or_circ->crypto.b_crypto, cell->payload);
 }
@@ -229,6 +241,7 @@ relay_crypto_clear(relay_crypto_t *crypto)
   crypto_cipher_free(crypto->b_crypto);
   crypto_digest_free(crypto->f_digest);
   crypto_digest_free(crypto->b_digest);
+  crypto_digest_free(crypto->sendme_digest);
 }
 
 /** Initialize <b>crypto</b> from the key material in key_data.
diff --git a/src/core/or/relay.c b/src/core/or/relay.c
index b26360b245..47275a811e 100644
--- a/src/core/or/relay.c
+++ b/src/core/or/relay.c
@@ -1568,7 +1568,7 @@ connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ,
       }
 
       /* Consider sending a circuit-level SENDME cell. */
-      sendme_circuit_consider_sending(circ, layer_hint, NULL);
+      sendme_circuit_consider_sending(circ, layer_hint);
 
       if (rh.stream_id == 0) {
         log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Relay data cell with zero "
diff --git a/src/core/or/relay_crypto_st.h b/src/core/or/relay_crypto_st.h
index dafce257c7..dbdf1599dc 100644
--- a/src/core/or/relay_crypto_st.h
+++ b/src/core/or/relay_crypto_st.h
@@ -25,6 +25,8 @@ struct relay_crypto_t {
   /** Digest state for cells heading away from the OR at this step. */
   struct crypto_digest_t *b_digest;
 
+  /** Digest used for the next SENDME cell if any. */
+  struct crypto_digest_t *sendme_digest;
 };
 #undef crypto_cipher_t
 
diff --git a/src/core/or/sendme.c b/src/core/or/sendme.c
index afade43f74..76f551a929 100644
--- a/src/core/or/sendme.c
+++ b/src/core/or/sendme.c
@@ -14,6 +14,7 @@
 #include "core/or/cell_st.h"
 #include "core/or/circuitlist.h"
 #include "core/or/circuituse.h"
+#include "core/or/or_circuit_st.h"
 #include "core/or/relay.h"
 #include "core/or/sendme.h"
 #include "feature/nodelist/networkstatus.h"
@@ -342,18 +343,20 @@ sendme_connection_edge_consider_sending(edge_connection_t *conn)
  * more.
  */
 void
-sendme_circuit_consider_sending(circuit_t *circ, crypt_path_t *layer_hint,
-                                crypto_digest_t *digest)
+sendme_circuit_consider_sending(circuit_t *circ, crypt_path_t *layer_hint)
 {
-  tor_assert(digest);
+  crypto_digest_t *digest;
 
   while ((layer_hint ? layer_hint->deliver_window : circ->deliver_window) <=
           CIRCWINDOW_START - CIRCWINDOW_INCREMENT) {
     log_debug(LD_CIRC,"Queuing circuit sendme.");
-    if (layer_hint)
+    if (layer_hint) {
       layer_hint->deliver_window += CIRCWINDOW_INCREMENT;
-    else
+      digest = layer_hint->crypto.sendme_digest;
+    } else {
       circ->deliver_window += CIRCWINDOW_INCREMENT;
+      digest = TO_OR_CIRCUIT(circ)->crypto.sendme_digest;
+    }
     if (send_circuit_level_sendme(circ, layer_hint, digest) < 0) {
       return; /* The circuit's closed, don't continue */
     }
@@ -557,9 +560,16 @@ sendme_note_cell_digest(circuit_t *circ)
     return;
   }
 
-  digest = tor_malloc_zero(4);
-  if (circ->sendme_last_digests == NULL) {
-    circ->sendme_last_digests = smartlist_new();
+  /* Only note the digest if we actually have the digest of the previous cell
+   * recorded. It should never happen in theory as we always record the last
+   * digest for the v1 SENDME. */
+  if (TO_OR_CIRCUIT(circ)->crypto.sendme_digest) {
+    digest = tor_malloc_zero(4);
+    crypto_digest_get_digest(TO_OR_CIRCUIT(circ)->crypto.sendme_digest,
+                             (char *) digest, 4);
+    if (circ->sendme_last_digests == NULL) {
+      circ->sendme_last_digests = smartlist_new();
+    }
+    smartlist_add(circ->sendme_last_digests, digest);
   }
-  smartlist_add(circ->sendme_last_digests, digest);
 }
diff --git a/src/core/or/sendme.h b/src/core/or/sendme.h
index 300fb25d96..e7cf718bb1 100644
--- a/src/core/or/sendme.h
+++ b/src/core/or/sendme.h
@@ -16,8 +16,7 @@
 /* Sending SENDME cell. */
 void sendme_connection_edge_consider_sending(edge_connection_t *edge_conn);
 void sendme_circuit_consider_sending(circuit_t *circ,
-                                     crypt_path_t *layer_hint,
-                                     crypto_digest_t *digest);
+                                     crypt_path_t *layer_hint);
 
 /* Processing SENDME cell. */
 int sendme_process_circuit_level(crypt_path_t *layer_hint,