diff --git a/src/main/java/com/microsoft/azure/proton/transport/proxy/impl/ProxyImpl.java b/src/main/java/com/microsoft/azure/proton/transport/proxy/impl/ProxyImpl.java
index ac9a121..697ab6b 100644
--- a/src/main/java/com/microsoft/azure/proton/transport/proxy/impl/ProxyImpl.java
+++ b/src/main/java/com/microsoft/azure/proton/transport/proxy/impl/ProxyImpl.java
@@ -278,7 +278,7 @@ public void process() throws TransportException {
                         if (LOGGER.isErrorEnabled()) {
                             LOGGER.error("Proxy authentication required. User configured: '{}', but supported proxy authentication methods are: {}",
                                 proxyConfiguration.authentication(),
-                                supportedTypes.stream().map(Enum::toString).collect(Collectors.joining(",")));
+                                supportedTypes.stream().map(type -> type.toString()).collect(Collectors.joining(",")));
                         }
                         closeTailProxyError(PROXY_CONNECT_USER_ERROR + PROXY_CONNECT_FAILED
                                 + result.getResponse().toString());