diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 58fc5e5..05778cd 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -24,6 +24,7 @@
 #include "mbedtls/private_access.h"
 
 #include "mbedtls/build_info.h"
+#include "mbedtls/platform_util.h"
 
 #include "mbedtls/bignum.h"
 
@@ -1327,10 +1328,11 @@
 int mbedtls_ecp_read_key(mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
                          const unsigned char *buf, size_t buflen);
 
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
 /**
  * \brief           This function exports an elliptic curve private key.
  *
- * \note            Note that although this function accepts an output
+ * \deprecated      Note that although this function accepts an output
  *                  buffer that is smaller or larger than the key, most key
  *                  import interfaces require the output to have exactly
  *                  key's nominal length. It is generally simplest to
@@ -1340,6 +1342,8 @@
  *                  how to calculate the nominal length.
  *                  To avoid this difficulty, use mbedtls_ecp_write_key_ext()
  *                  instead.
+ *                  mbedtls_ecp_write_key() is deprecated and will be
+ *                  removed in a future version of the library.
  *
  * \note            If the private key was not set in \p key,
  *                  the output is unspecified. Future versions
@@ -1369,8 +1373,9 @@
  *                  representation is larger than the available space in \p buf.
  * \return          Another negative error code on different kinds of failure.
  */
-int mbedtls_ecp_write_key(mbedtls_ecp_keypair *key,
-                          unsigned char *buf, size_t buflen);
+int MBEDTLS_DEPRECATED mbedtls_ecp_write_key(mbedtls_ecp_keypair *key,
+                                             unsigned char *buf, size_t buflen);
+#endif /* MBEDTLS_DEPRECATED_REMOVED */
 
 /**
  * \brief           This function exports an elliptic curve private key.