diff --git a/lib/isc/unix/include/isc/net.h b/lib/isc/unix/include/isc/net.h
index 7bf6b089dc..812a94349d 100644
--- a/lib/isc/unix/include/isc/net.h
+++ b/lib/isc/unix/include/isc/net.h
@@ -387,6 +387,7 @@ isc_net_getudpportrange(int af, in_port_t *low, in_port_t *high);
 #ifdef ISC_PLATFORM_NEEDNTOP
 const char *
 isc_net_ntop(int af, const void *src, char *dst, size_t size);
+#undef inet_ntop
 #define inet_ntop isc_net_ntop
 #endif
 
diff --git a/lib/isc/win32/include/isc/net.h b/lib/isc/win32/include/isc/net.h
index ef69ad32d5..1d67c29eed 100644
--- a/lib/isc/win32/include/isc/net.h
+++ b/lib/isc/win32/include/isc/net.h
@@ -393,6 +393,7 @@ isc_net_getudpportrange(int af, in_port_t *low, in_port_t *high);
 #ifdef ISC_PLATFORM_NEEDNTOP
 const char *
 isc_net_ntop(int af, const void *src, char *dst, size_t size);
+#undef inet_ntop
 #define inet_ntop isc_net_ntop
 #endif