diff --git a/dlls/mountmgr.sys/device.c b/dlls/mountmgr.sys/device.c
index 7ee407886c5..5003d4d2ea3 100644
--- a/dlls/mountmgr.sys/device.c
+++ b/dlls/mountmgr.sys/device.c
@@ -27,6 +27,8 @@
 #include <stdio.h>
 #include <sys/time.h>
 
+#define NONAMELESSUNION
+
 #include "mountmgr.h"
 #include "winreg.h"
 #include "winuser.h"
diff --git a/dlls/mountmgr.sys/mountmgr.c b/dlls/mountmgr.sys/mountmgr.c
index d7bc8d7ef79..10286dc2de2 100644
--- a/dlls/mountmgr.sys/mountmgr.c
+++ b/dlls/mountmgr.sys/mountmgr.c
@@ -22,7 +22,6 @@
 #include <unistd.h>
 
 #define NONAMELESSUNION
-#define NONAMELESSSTRUCT
 
 #include "mountmgr.h"
 #include "winreg.h"
diff --git a/dlls/mountmgr.sys/mountmgr.h b/dlls/mountmgr.sys/mountmgr.h
index d1e814f0e44..2f0db62c875 100644
--- a/dlls/mountmgr.sys/mountmgr.h
+++ b/dlls/mountmgr.sys/mountmgr.h
@@ -20,9 +20,6 @@
 
 #include <stdarg.h>
 
-#define NONAMELESSUNION
-#define NONAMELESSSTRUCT
-
 #include "ntstatus.h"
 #define WIN32_NO_STATUS
 #include "windef.h"