diff --git a/include/Makefile.in b/include/Makefile.in
index 5b84d7858ff..4a8c261bb8f 100644
--- a/include/Makefile.in
+++ b/include/Makefile.in
@@ -524,6 +524,7 @@ SOURCES = \
 	netcon.idl \
 	netfw.idl \
 	netioapi.h \
+	netiodef.h \
 	netlistmgr.idl \
 	newdev.h \
 	nldef.h \
diff --git a/include/netiodef.h b/include/netiodef.h
new file mode 100644
index 00000000000..611359c49f8
--- /dev/null
+++ b/include/netiodef.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2021 Huw Davies
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#ifndef __WINE_NETIODEF_H
+#define __WINE_NETIODEF_H
+
+typedef enum _NPI_MODULEID_TYPE
+{
+    MIT_GUID = 1,
+    MIT_IF_LUID
+} NPI_MODULEID_TYPE;
+
+typedef struct _NPI_MODULEID
+{
+    USHORT Length;
+    NPI_MODULEID_TYPE Type;
+    union
+    {
+        GUID Guid;
+        LUID IfLuid;
+    };
+} NPI_MODULEID;
+
+typedef const NPI_MODULEID *PNPI_MODULEID;
+
+static inline BOOLEAN NmrIsEqualNpiModuleId( const NPI_MODULEID *mod1, const NPI_MODULEID *mod2 )
+{
+    if (mod1->Type == mod2->Type)
+    {
+        if (mod1->Type == MIT_GUID)
+        {
+#ifdef __cplusplus
+            return IsEqualGUID( mod1->Guid, mod2->Guid );
+#else
+            return IsEqualGUID( &mod1->Guid, &mod2->Guid );
+#endif
+        }
+        else if (mod1->Type == MIT_IF_LUID)
+            return mod1->IfLuid.HighPart == mod2->IfLuid.HighPart &&
+                mod1->IfLuid.LowPart == mod2->IfLuid.LowPart;
+    }
+    return FALSE;
+}
+
+#endif /* __WINE_NETIODEF_H */