diff --git a/runtime/include/http_response.h b/runtime/include/http_response.h
index 27b401f..f02a769 100644
--- a/runtime/include/http_response.h
+++ b/runtime/include/http_response.h
@@ -10,7 +10,7 @@
 #include "http.h"
 
 #define HTTP_RESPONSE_200_OK                    "HTTP/1.1 200 OK\r\n"
-#define HTTP_RESPONSE_504_SERVICE_UNAVAILABLE   "HTTP/1.1 504 Service Unavailable\r\n\r\n"
+#define HTTP_RESPONSE_503_SERVICE_UNAVAILABLE   "HTTP/1.1 503 Service Unavailable\r\n\r\n"
 #define HTTP_RESPONSE_400_BAD_REQUEST           "HTTP/1.1 400 Bad Request\r\n\r\n"
 #define HTTP_RESPONSE_CONTENT_LENGTH            "Content-Length: "
 #define HTTP_RESPONSE_CONTENT_LENGTH_TERMINATOR "\r\n\r\n" /* content body follows this */
diff --git a/runtime/src/runtime.c b/runtime/src/runtime.c
index 157e476..2cf0592 100644
--- a/runtime/src/runtime.c
+++ b/runtime/src/runtime.c
@@ -162,10 +162,10 @@ listener_thread_reject(int client_socket)
 
 	int rc;
 	int sent    = 0;
-	int to_send = strlen(HTTP_RESPONSE_504_SERVICE_UNAVAILABLE);
+	int to_send = strlen(HTTP_RESPONSE_503_SERVICE_UNAVAILABLE);
 
 	while (sent < to_send) {
-		rc = write(client_socket, &HTTP_RESPONSE_504_SERVICE_UNAVAILABLE[sent], to_send - sent);
+		rc = write(client_socket, &HTTP_RESPONSE_503_SERVICE_UNAVAILABLE[sent], to_send - sent);
 		if (rc < 0) {
 			if (errno == EAGAIN) continue;