diff --git a/src/tcp_socket.c b/src/tcp_socket.c
index 21b77b5..e8ee1fc 100644
--- a/src/tcp_socket.c
+++ b/src/tcp_socket.c
@@ -104,7 +104,7 @@ int create_tcp_socket(unsigned short port) {
 }
 
 void cleanup_tcp_socket(int *tcp_socket) {
-  if (tcp_socket && *tcp_socket != -1) {
+  if (tcp_socket && *tcp_socket >= 0) {
     close(*tcp_socket);
     *tcp_socket = -1;
   }