diff --git a/src/TLSClient.cpp b/src/TLSClient.cpp
index c130d0cf6..b4a540fa8 100644
--- a/src/TLSClient.cpp
+++ b/src/TLSClient.cpp
@@ -30,6 +30,7 @@
 #ifdef HAVE_LIBGNUTLS
 
 #include <iostream>
+#include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>