diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index f405065..494f8c2 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1266,6 +1266,21 @@
     char own_verify_data[MBEDTLS_SSL_VERIFY_DATA_MAX_LEN]; /*!<  previous handshake verify data */
     char peer_verify_data[MBEDTLS_SSL_VERIFY_DATA_MAX_LEN]; /*!<  previous handshake verify data */
 #endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+#if defined(MBEDTLS_SSL_CID)
+    /* CID configuration to use in subsequent handshakes. */
+
+    /*! The next incoming CID, chosen by the user and applying to
+     *  all subsequent handshakes. This may be different from the
+     *  CID currently used in case the user has re-configured the CID
+     *  after an initial handshake. */
+    unsigned char own_cid[ MBEDTLS_SSL_CID_IN_LEN_MAX ];
+    uint8_t own_cid_len;   /*!< The length of \c own_cid. */
+    uint8_t negotiate_cid; /*!< This indicates whether the CID extension should
+                            *   be negotiated in the next handshake or not.
+                            *   Possible values are #MBEDTLS_SSL_CID_ENABLED
+                            *   and #MBEDTLS_SSL_CID_DISABLED. */
+#endif /* MBEDTLS_SSL_CID */
 };
 
 #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 9c4be53..e4d0a4c 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -372,6 +372,18 @@
     unsigned char alt_out_ctr[8];       /*!<  Alternative record epoch/counter
                                               for resending messages         */
 
+#if defined(MBEDTLS_SSL_CID)
+    /* The state of CID configuration in this handshake. */
+
+    uint8_t cid_in_use; /*!< This indicates whether the use of the CID extension
+                         *   has been negotited. Possible values are
+                         *   #MBEDTLS_SSL_CID_ENABLED and
+                         *   #MBEDTLS_SSL_CID_DISABLED. */
+    unsigned char peer_cid[ MBEDTLS_SSL_CID_OUT_LEN_MAX ]; /*! The peer's CID */
+    uint8_t peer_cid_len;                                  /*!< The length of
+                                                            *   \c peer_cid.  */
+#endif /* MBEDTLS_SSL_CID */
+
     struct
     {
         size_t total_bytes_buffered; /*!< Cumulative size of heap allocated