diff --git a/src/os/win32/sigar_os.h b/src/os/win32/sigar_os.h
index 91ce12aa..de626e53 100644
--- a/src/os/win32/sigar_os.h
+++ b/src/os/win32/sigar_os.h
@@ -19,6 +19,10 @@
 #ifndef SIGAR_OS_H
 #define SIGAR_OS_H
 
+#if _MSC_VER <= 1200
+#define SIGAR_USING_MSC6 /* Visual Studio version 6 */
+#endif
+
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #include <winreg.h>
@@ -144,7 +148,7 @@ typedef struct _WINSTATION_INFO {
 
 /* end wtsapi32.h */
 
-#if _MSC_VER <= 1200
+#ifdef SIGAR_USING_MSC6
 
 /* from winbase.h not in vs6.0 */
 typedef struct {
diff --git a/src/os/win32/win32_sigar.c b/src/os/win32/win32_sigar.c
index 88130493..4733d87d 100644
--- a/src/os/win32/win32_sigar.c
+++ b/src/os/win32/win32_sigar.c
@@ -2225,7 +2225,7 @@ static int sigar_get_netif_ipaddr(sigar_t *sigar,
             MIB_IPADDRROW *row = &mib->table[i];
             short type;
 
-#if _MSC_VER <= 1200
+#ifdef SIGAR_USING_MSC6
             type = row->unused2;
 #else
             type = row->wType;
@@ -3297,7 +3297,7 @@ int sigar_who_list_get_win32(sigar_t *sigar,
 #define VER_NT_WORKSTATION 0x0000001
 #endif
 
-#if _MSC_VER <= 1200
+#if SIGAR_USING_MSC6
 #define sigar_wProductType wReserved[1]
 #else
 #define sigar_wProductType wProductType