diff --git a/tests/testutil.hpp b/tests/testutil.hpp
index c6f5e4de78..09b9fa77e5 100644
--- a/tests/testutil.hpp
+++ b/tests/testutil.hpp
@@ -41,6 +41,9 @@
 //  For AF_INET and IPPROTO_TCP
 #if defined _WIN32
 #include "../src/windows.hpp"
+#if defined(__MINGW32__)
+#include <unistd.h>
+#endif
 #else
 #include <arpa/inet.h>
 #include <unistd.h>
