diff --git a/src/cli/cli.cpp b/src/cli/cli.cpp
index 8b258f5fa..53aec416d 100644
--- a/src/cli/cli.cpp
+++ b/src/cli/cli.cpp
@@ -115,6 +115,10 @@ int main(int argc, const char* argv[]) {
 
   std::string remote_host_ips;
   uint16_t remote_port = absl::GetFlag(FLAGS_server_port);
+  if (remote_port == 0u) {
+    LOG(WARNING) << "Invalid server port: " << remote_port;
+    return -1;
+  }
 
   auto results = ResolveAddress(remote_host_name, remote_port);
   if (results.empty()) {
diff --git a/src/config/config.cpp b/src/config/config.cpp
index fc9cfebca..8fee07d4c 100644
--- a/src/config/config.cpp
+++ b/src/config/config.cpp
@@ -139,7 +139,7 @@ std::string ReadConfigFromArgument(std::string_view server_host,
   }
 
   auto server_port = StringToIntegerU(_server_port);
-  if (!server_port.has_value() || server_port.value() > 65535u) {
+  if (!server_port.has_value() || server_port.value() == 0u || server_port.value() > 65535u) {
     err_msg << ",Invalid Server Port: " << _server_port;
   }
 
@@ -218,7 +218,7 @@ std::string ReadConfigFromArgument(std::string_view server_host,
   }
 
   auto server_port = StringToIntegerU(_server_port);
-  if (!server_port.has_value() || server_port.value() > 65535u) {
+  if (!server_port.has_value() || server_port.value() == 0u || server_port.value() > 65535u) {
     err_msg << ",Invalid Server Port: " << _server_port;
   }
 
diff --git a/src/server/server.cpp b/src/server/server.cpp
index 5d79dbe03..99b5a1392 100644
--- a/src/server/server.cpp
+++ b/src/server/server.cpp
@@ -120,6 +120,10 @@ int main(int argc, const char* argv[]) {
   std::string host_name = absl::GetFlag(FLAGS_server_host);
   std::string host_sni = host_name;
   uint16_t port = absl::GetFlag(FLAGS_server_port);
+  if (port == 0u) {
+    LOG(WARNING) << "Invalid server port: " << port;
+    return -1;
+  }
 
   asio::error_code ec;
   auto addr = asio::ip::make_address(host_name.c_str(), ec);