diff --git a/system/jlib/jsocket.cpp b/system/jlib/jsocket.cpp
index aeb43db82bc..5feca3b99a9 100644
--- a/system/jlib/jsocket.cpp
+++ b/system/jlib/jsocket.cpp
@@ -478,6 +478,9 @@ static int getAddressInfo(const char *name, unsigned *netaddr, bool okToLogErr);
 
 static CriticalSection queryDNSCS;
 
+#ifndef EAI_SYSTEM
+#   define EAI_SYSTEM -11
+#endif
 class CAddrInfoThreadArgs : public CInterface
 {
 public: