diff --git a/Net/src/HTTPClientSession.cpp b/Net/src/HTTPClientSession.cpp
index 0fa57689b1..323e9526df 100644
--- a/Net/src/HTTPClientSession.cpp
+++ b/Net/src/HTTPClientSession.cpp
@@ -429,8 +429,13 @@ std::string HTTPClientSession::proxyRequestPrefix() const
 {
 	std::string result("http://");
 	result.append(_host);
-	result.append(":");
-	NumberFormatter::append(result, _port);
+	/// Do not append default by default, since this may break some servers.
+	/// One example of such server is GCS (Google Cloud Storage).
+	if (_port != HTTPSession::HTTP_PORT)
+	{
+		result.append(":");
+		NumberFormatter::append(result, _port);
+	}
 	return result;
 }
 
diff --git a/NetSSL_OpenSSL/src/HTTPSClientSession.cpp b/NetSSL_OpenSSL/src/HTTPSClientSession.cpp
index 62b6f6e3ed..91c87bd70b 100644
--- a/NetSSL_OpenSSL/src/HTTPSClientSession.cpp
+++ b/NetSSL_OpenSSL/src/HTTPSClientSession.cpp
@@ -138,8 +138,13 @@ std::string HTTPSClientSession::proxyRequestPrefix() const
 {
 	std::string result("https://");
 	result.append(getHost());
-	result.append(":");
-	NumberFormatter::append(result, getPort());
+	/// Do not append default by default, since this may break some servers.
+	/// One example of such server is GCS (Google Cloud Storage).
+	if (getPort() != HTTPS_PORT)
+	{
+		result.append(":");
+		NumberFormatter::append(result, getPort());
+	}
 	return result;
 }