diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 350ee2c..d11db3f 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1615,8 +1615,12 @@
     /*
      * PKI layer
      */
-    int MBEDTLS_PRIVATE(client_auth);                    /*!<  flag for client auth.   */
-
+#if defined(MBEDTLS_SSL_CLI_C)
+    int MBEDTLS_PRIVATE(client_auth);           /*!< used to check if CertificateRequest is
+                                                     received from server side. If
+                                                     CertificateReqeust is received, Certificate
+                                                     and CertificateVerify should be sent to server */
+#endif /* MBEDTLS_SSL_CLI_C */
     /*
      * User settings
      */