diff --git a/dlls/ws2_32/socket.c b/dlls/ws2_32/socket.c
index 69fbb37af22..d7eddde44d8 100644
--- a/dlls/ws2_32/socket.c
+++ b/dlls/ws2_32/socket.c
@@ -4554,8 +4554,8 @@ static const char *debugstr_wsaioctl(DWORD code)
         IOCTL_NAME(WS_SIO_GET_INTERFACE_LIST);
         /* IOCTL_NAME(WS_SIO_GET_INTERFACE_LIST_EX); */
         IOCTL_NAME(WS_SIO_GET_QOS);
-        /* IOCTL_NAME(WS_SIO_IDEAL_SEND_BACKLOG_CHANGE);
-        IOCTL_NAME(WS_SIO_IDEAL_SEND_BACKLOG_QUERY); */
+        IOCTL_NAME(WS_SIO_IDEAL_SEND_BACKLOG_CHANGE);
+        IOCTL_NAME(WS_SIO_IDEAL_SEND_BACKLOG_QUERY);
         IOCTL_NAME(WS_SIO_KEEPALIVE_VALS);
         IOCTL_NAME(WS_SIO_MULTIPOINT_LOOPBACK);
         IOCTL_NAME(WS_SIO_MULTICAST_SCOPE);
diff --git a/include/ws2ipdef.h b/include/ws2ipdef.h
index 4cae361e5fe..fc465804962 100644
--- a/include/ws2ipdef.h
+++ b/include/ws2ipdef.h
@@ -282,6 +282,14 @@ typedef struct WS(in_pktinfo) {
 
 #define SS_PORT(ssp) (((PSOCKADDR_IN)(ssp))->sin_port)
 
+#ifndef USE_WS_PREFIX
+#define SIO_IDEAL_SEND_BACKLOG_CHANGE _IO ('t', 122)
+#define SIO_IDEAL_SEND_BACKLOG_QUERY  _IOR('t', 123, ULONG)
+#else
+#define WS_SIO_IDEAL_SEND_BACKLOG_CHANGE WS__IO ('t', 122)
+#define WS_SIO_IDEAL_SEND_BACKLOG_QUERY  WS__IOR('t', 123, ULONG)
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif