diff --git a/library/common.h b/library/common.h
index 839b7d1..ce92238 100644
--- a/library/common.h
+++ b/library/common.h
@@ -114,6 +114,18 @@
  */
 #define MBEDTLS_ALLOW_PRIVATE_ACCESS
 
+/**
+ * \brief       Securely zeroize a buffer then free it.
+ *
+ *              Exactly the same as consecutive calls to
+ *              \c mbedtls_platform_zeroize() and \c mbedtls_free(), but has a
+ *              code size savings, and potential for optimisation in the future.
+ *
+ * \param buf   Buffer to be zeroized then freed. May be \c NULL.
+ * \param len   Length of the buffer in bytes
+ */
+void mbedtls_zeroize_and_free(void *buf, size_t len);
+
 /** Return an offset into a buffer.
  *
  * This is just the addition of an offset to a pointer, except that this