diff --git a/src/libCom/misc/aToIPAddr.c b/src/libCom/misc/aToIPAddr.c
index a3ef16987..13d6fa7f5 100644
--- a/src/libCom/misc/aToIPAddr.c
+++ b/src/libCom/misc/aToIPAddr.c
@@ -9,6 +9,7 @@
 #include <string.h>
 
 #define epicsExportSharedSymbols
+#include "osiSock.h"
 
 #ifndef LOCAL
 #define LOCAL static