diff --git a/ChangeLog b/ChangeLog
index e6df8fb6e..88a3d3a8f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -51,6 +51,8 @@ Changes
    * Change the use of Windows threading to use Microsoft Visual C++ runtime
      calls, rather than Win32 API calls directly. This is necessary to avoid
      conflict with C runtime usage. Found and fixed by irwir.
+   * Improve documentation of mbedtls_ssl_get_verify_result().
+     Fixes #517 reported by github-monoculture.
 
 = mbed TLS 2.1.15 branch released 2018-08-31
 
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index d98e5ed9e..1fe8d8c86 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1998,13 +1998,14 @@ size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl );
 /**
  * \brief          Return the result of the certificate verification
  *
- * \param ssl      SSL context
+ * \param ssl      The SSL context to use.
  *
- * \return         0 if successful,
- *                 -1 if result is not available (eg because the handshake was
- *                 aborted too early), or
- *                 a combination of BADCERT_xxx and BADCRL_xxx flags, see
- *                 x509.h
+ * \return         \c 0 if the certificate verification was successful.
+ * \return         \c -1u if the result is not available. This may happen
+ *                 e.g. if the handshake aborts early, or a verification
+ *                 callback returned a fatal error.
+ * \return         A bitwise combination of \c MBEDTLS_X509_BADCERT_XXX
+ *                 and \c MBEDTLS_X509_BADCRL_XXX failure flags; see x509.h.
  */
 uint32_t mbedtls_ssl_get_verify_result( const mbedtls_ssl_context *ssl );