diff --git a/ssl/d1_both.cc b/ssl/d1_both.cc
index b910b96d9..1a68d93bd 100644
--- a/ssl/d1_both.cc
+++ b/ssl/d1_both.cc
@@ -624,16 +624,14 @@ static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out,
   assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len);
   assert(msg == &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]);
 
-  enum dtls1_use_epoch_t use_epoch = dtls1_use_current_epoch;
-  if (ssl->d1->w_epoch >= 1 && msg->epoch == ssl->d1->w_epoch - 1) {
-    use_epoch = dtls1_use_previous_epoch;
-  } else if (msg->epoch != ssl->d1->w_epoch) {
+  if (msg->epoch != ssl->d1->w_epoch &&
+      (ssl->d1->w_epoch == 0 || msg->epoch != ssl->d1->w_epoch - 1)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return seal_error;
   }
 
-  size_t overhead = dtls_max_seal_overhead(ssl, use_epoch);
-  size_t prefix = dtls_seal_prefix_len(ssl, use_epoch);
+  size_t overhead = dtls_max_seal_overhead(ssl, msg->epoch);
+  size_t prefix = dtls_seal_prefix_len(ssl, msg->epoch);
 
   if (msg->is_ccs) {
     // Check there is room for the ChangeCipherSpec.
@@ -644,7 +642,7 @@ static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out,
 
     if (!dtls_seal_record(ssl, out, out_len, max_out,
                           SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec,
-                          sizeof(kChangeCipherSpec), use_epoch)) {
+                          sizeof(kChangeCipherSpec), msg->epoch)) {
       return seal_error;
     }
 
@@ -697,7 +695,7 @@ static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out,
                       MakeSpan(frag, frag_len));
 
   if (!dtls_seal_record(ssl, out, out_len, max_out, SSL3_RT_HANDSHAKE,
-                        out + prefix, frag_len, use_epoch)) {
+                        out + prefix, frag_len, msg->epoch)) {
     return seal_error;
   }
 
diff --git a/ssl/d1_pkt.cc b/ssl/d1_pkt.cc
index b86615626..da898b499 100644
--- a/ssl/d1_pkt.cc
+++ b/ssl/d1_pkt.cc
@@ -208,7 +208,7 @@ int dtls1_write_app_data(SSL *ssl, bool *out_needs_handshake,
   }
 
   int ret = dtls1_write_record(ssl, SSL3_RT_APPLICATION_DATA, in,
-                               dtls1_use_current_epoch);
+                               ssl->d1->w_epoch);
   if (ret <= 0) {
     return ret;
   }
@@ -217,7 +217,7 @@ int dtls1_write_app_data(SSL *ssl, bool *out_needs_handshake,
 }
 
 int dtls1_write_record(SSL *ssl, int type, Span<const uint8_t> in,
-                       enum dtls1_use_epoch_t use_epoch) {
+                       uint16_t epoch) {
   SSLBuffer *buf = &ssl->s3->write_buffer;
   assert(in.size() <= SSL3_RT_MAX_PLAIN_LENGTH);
   // There should never be a pending write buffer in DTLS. One can't write half
@@ -235,7 +235,7 @@ int dtls1_write_record(SSL *ssl, int type, Span<const uint8_t> in,
                       in.size() + SSL_max_seal_overhead(ssl)) ||
       !dtls_seal_record(ssl, buf->remaining().data(), &ciphertext_len,
                         buf->remaining().size(), type, in.data(), in.size(),
-                        use_epoch)) {
+                        epoch)) {
     buf->Clear();
     return -1;
   }
@@ -250,7 +250,7 @@ int dtls1_write_record(SSL *ssl, int type, Span<const uint8_t> in,
 
 int dtls1_dispatch_alert(SSL *ssl) {
   int ret = dtls1_write_record(ssl, SSL3_RT_ALERT, ssl->s3->send_alert,
-                               dtls1_use_current_epoch);
+                               ssl->d1->w_epoch);
   if (ret <= 0) {
     return ret;
   }
diff --git a/ssl/dtls_record.cc b/ssl/dtls_record.cc
index 068864fae..6551aa45d 100644
--- a/ssl/dtls_record.cc
+++ b/ssl/dtls_record.cc
@@ -258,29 +258,30 @@ enum ssl_open_record_t dtls_open_record(SSL *ssl, uint8_t *out_type,
 }
 
 static const SSLAEADContext *get_write_aead(const SSL *ssl,
-                                            enum dtls1_use_epoch_t use_epoch) {
-  if (use_epoch == dtls1_use_previous_epoch) {
-    assert(ssl->d1->w_epoch >= 1);
+                                            uint16_t epoch) {
+  if (epoch < ssl->d1->w_epoch) {
+    assert(epoch + 1 == ssl->d1->w_epoch);
     return ssl->d1->last_aead_write_ctx.get();
   }
 
+  assert(epoch == ssl->d1->w_epoch);
   return ssl->s3->aead_write_ctx.get();
 }
 
 size_t dtls_max_seal_overhead(const SSL *ssl,
-                              enum dtls1_use_epoch_t use_epoch) {
-  return DTLS1_RT_HEADER_LENGTH + get_write_aead(ssl, use_epoch)->MaxOverhead();
+                              uint16_t epoch) {
+  return DTLS1_RT_HEADER_LENGTH + get_write_aead(ssl, epoch)->MaxOverhead();
 }
 
-size_t dtls_seal_prefix_len(const SSL *ssl, enum dtls1_use_epoch_t use_epoch) {
+size_t dtls_seal_prefix_len(const SSL *ssl, uint16_t epoch) {
   return DTLS1_RT_HEADER_LENGTH +
-         get_write_aead(ssl, use_epoch)->ExplicitNonceLen();
+         get_write_aead(ssl, epoch)->ExplicitNonceLen();
 }
 
 bool dtls_seal_record(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
                       uint8_t type, const uint8_t *in, size_t in_len,
-                      enum dtls1_use_epoch_t use_epoch) {
-  const size_t prefix = dtls_seal_prefix_len(ssl, use_epoch);
+                      uint16_t epoch) {
+  const size_t prefix = dtls_seal_prefix_len(ssl, epoch);
   if (buffers_alias(in, in_len, out, max_out) &&
       (max_out < prefix || out + prefix != in)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT);
@@ -288,14 +289,14 @@ bool dtls_seal_record(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
   }
 
   // Determine the parameters for the current epoch.
-  uint16_t epoch = ssl->d1->w_epoch;
   SSLAEADContext *aead = ssl->s3->aead_write_ctx.get();
   uint64_t *seq = &ssl->s3->write_sequence;
-  if (use_epoch == dtls1_use_previous_epoch) {
-    assert(ssl->d1->w_epoch >= 1);
-    epoch = ssl->d1->w_epoch - 1;
+  if (epoch < ssl->d1->w_epoch) {
+    assert(epoch + 1 == ssl->d1->w_epoch);
     aead = ssl->d1->last_aead_write_ctx.get();
     seq = &ssl->d1->last_write_sequence;
+  } else {
+    assert(epoch == ssl->d1->w_epoch);
   }
 
   if (max_out < DTLS1_RT_HEADER_LENGTH) {
diff --git a/ssl/internal.h b/ssl/internal.h
index 2e4464163..4db9f1750 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -1044,26 +1044,21 @@ size_t ssl_seal_align_prefix_len(const SSL *ssl);
 bool tls_seal_record(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
                      uint8_t type, const uint8_t *in, size_t in_len);
 
-enum dtls1_use_epoch_t {
-  dtls1_use_previous_epoch,
-  dtls1_use_current_epoch,
-};
-
 // dtls_max_seal_overhead returns the maximum overhead, in bytes, of sealing a
 // record.
-size_t dtls_max_seal_overhead(const SSL *ssl, enum dtls1_use_epoch_t use_epoch);
+size_t dtls_max_seal_overhead(const SSL *ssl, uint16_t epoch);
 
 // dtls_seal_prefix_len returns the number of bytes of prefix to reserve in
 // front of the plaintext when sealing a record in-place.
-size_t dtls_seal_prefix_len(const SSL *ssl, enum dtls1_use_epoch_t use_epoch);
+size_t dtls_seal_prefix_len(const SSL *ssl, uint16_t epoch);
 
-// dtls_seal_record implements |tls_seal_record| for DTLS. |use_epoch| selects
-// which epoch's cipher state to use. Unlike |tls_seal_record|, |in| and |out|
-// may alias but, if they do, |in| must be exactly |dtls_seal_prefix_len| bytes
+// dtls_seal_record implements |tls_seal_record| for DTLS. |epoch| selects which
+// epoch's cipher state to use. Unlike |tls_seal_record|, |in| and |out| may
+// alias but, if they do, |in| must be exactly |dtls_seal_prefix_len| bytes
 // ahead of |out|.
 bool dtls_seal_record(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
                       uint8_t type, const uint8_t *in, size_t in_len,
-                      enum dtls1_use_epoch_t use_epoch);
+                      uint16_t epoch);
 
 // ssl_process_alert processes |in| as an alert and updates |ssl|'s shutdown
 // state. It returns one of |ssl_open_record_discard|, |ssl_open_record_error|,
@@ -3379,7 +3374,7 @@ int dtls1_write_app_data(SSL *ssl, bool *out_needs_handshake,
 // dtls1_write_record sends a record. It returns one on success and <= 0 on
 // error.
 int dtls1_write_record(SSL *ssl, int type, Span<const uint8_t> in,
-                       enum dtls1_use_epoch_t use_epoch);
+                       uint16_t epoch);
 
 int dtls1_retransmit_outgoing_messages(SSL *ssl);
 bool dtls1_parse_fragment(CBS *cbs, struct hm_header_st *out_hdr,
diff --git a/ssl/tls_record.cc b/ssl/tls_record.cc
index 395b9a483..5a820f6d6 100644
--- a/ssl/tls_record.cc
+++ b/ssl/tls_record.cc
@@ -606,7 +606,7 @@ using namespace bssl;
 
 size_t SSL_max_seal_overhead(const SSL *ssl) {
   if (SSL_is_dtls(ssl)) {
-    return dtls_max_seal_overhead(ssl, dtls1_use_current_epoch);
+    return dtls_max_seal_overhead(ssl, ssl->d1->w_epoch);
   }
 
   size_t ret = SSL3_RT_HEADER_LENGTH;