diff --git a/lib/inet_ntop.h b/lib/inet_ntop.h
index 360ef3ae742c7213f93becb9e6641749f1709544..3d9f1dc760af589b216bd66a5fccbe33852d8924 100644
--- a/lib/inet_ntop.h
+++ b/lib/inet_ntop.h
@@ -31,7 +31,7 @@ char *Curl_inet_ntop(int af, const void *addr, char *buf, size_t size);
 #ifdef HAVE_ARPA_INET_H
 #include <arpa/inet.h>
 #endif
-#define Curl_inet_ntop(af,addr,buf,size) inet_ntop(af,addr,buf,(size_t)size)
+#define Curl_inet_ntop(af,addr,buf,size) inet_ntop(af,addr,buf,(socklen_t)size)
 #endif
 
 #endif /* __INET_NTOP_H */