diff --git a/include/guiddef.h b/include/guiddef.h
index 1871910efa1..546c4500434 100644
--- a/include/guiddef.h
+++ b/include/guiddef.h
@@ -30,7 +30,7 @@ typedef struct
 #else
 typedef struct _GUID
 {
-#ifdef _MSC_VER
+#ifdef WINE_USE_LONG
     unsigned long  Data1;
 #else
     unsigned int   Data1;
diff --git a/include/ntdef.h b/include/ntdef.h
index d85aa6feb5a..069e86575b8 100644
--- a/include/ntdef.h
+++ b/include/ntdef.h
@@ -53,7 +53,7 @@ typedef enum _WAIT_TYPE {
 #define BASETYPES
 typedef unsigned char UCHAR, *PUCHAR;
 typedef unsigned short USHORT, *PUSHORT;
-#ifdef _MSC_VER
+#ifdef WINE_USE_LONG
 typedef unsigned long ULONG, *PULONG;
 #else
 typedef unsigned int ULONG, *PULONG;
diff --git a/include/windef.h b/include/windef.h
index 436ac6afd87..7ece7c8628b 100644
--- a/include/windef.h
+++ b/include/windef.h
@@ -241,7 +241,7 @@ extern "C" {
 #define BASETYPES
 typedef unsigned char UCHAR, *PUCHAR;
 typedef unsigned short USHORT, *PUSHORT;
-#ifdef _MSC_VER
+#ifdef WINE_USE_LONG
 typedef unsigned long ULONG, *PULONG;
 #else
 typedef unsigned int ULONG, *PULONG;
@@ -257,7 +257,7 @@ typedef int             INT,        *PINT,     *LPINT;
 typedef unsigned int    UINT,       *PUINT;
 typedef float           FLOAT,      *PFLOAT;
 typedef char                        *PSZ;
-#ifdef _MSC_VER
+#ifdef WINE_USE_LONG
 typedef long                                   *LPLONG;
 typedef unsigned long   DWORD,      *PDWORD,   *LPDWORD;
 #else
diff --git a/include/winnt.h b/include/winnt.h
index 883794cde8c..cc2099086d6 100644
--- a/include/winnt.h
+++ b/include/winnt.h
@@ -452,7 +452,7 @@ typedef VOID           *PVOID64;
 typedef BYTE            BOOLEAN,    *PBOOLEAN;
 typedef char            CHAR,       *PCHAR;
 typedef short           SHORT,      *PSHORT;
-#ifdef _MSC_VER
+#ifdef WINE_USE_LONG
 typedef long            LONG,       *PLONG;
 #else
 typedef int             LONG,       *PLONG;