diff --git a/library/error.c b/library/error.c
index 151ca4e..490a040 100644
--- a/library/error.c
+++ b/library/error.c
@@ -441,6 +441,8 @@
             mbedtls_snprintf( buf, buflen, "SSL - The alert message received indicates a non-fatal error" );
         if( use_ret == -(MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH) )
             mbedtls_snprintf( buf, buflen, "SSL - Couldn't set the hash for verifying CertificateVerify" );
+        if( use_ret == -(MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS) )
+            mbedtls_snprintf( buf, buflen, "SSL - Asynchronous operation is not completed yet" );
 #endif /* MBEDTLS_SSL_TLS_C */
 
 #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C)