diff --git a/dlls/ndis.sys/ndis.sys.spec b/dlls/ndis.sys/ndis.sys.spec
index 1dd8b820d6a..bd83b487cc3 100644
--- a/dlls/ndis.sys/ndis.sys.spec
+++ b/dlls/ndis.sys/ndis.sys.spec
@@ -130,7 +130,7 @@
 @ stub NdisImmediateWritePortUshort
 @ stub NdisImmediateWriteSharedMemory
 @ stub NdisInitAnsiString
-@ stub NdisInitUnicodeString
+@ stdcall NdisInitUnicodeString(ptr wstr) ntdll.RtlInitUnicodeString
 @ stub NdisInitializeEvent
 @ stub NdisInitializeReadWriteLock
 @ stub NdisInitializeString