diff --git a/src/os/win32/win32_sigar.c b/src/os/win32/win32_sigar.c
index d89513ef..b267e83a 100644
--- a/src/os/win32/win32_sigar.c
+++ b/src/os/win32/win32_sigar.c
@@ -2736,11 +2736,11 @@ int sigar_os_sys_info_get(sigar_t *sigar,
     version.dwOSVersionInfoSize = sizeof(version);
     GetVersionEx(&version);
 
-    if (sigar->winnt) {
+    if (version.dwMajorVersion == 4) {
         vendor_name = "Windows NT";
         vendor_version = "NT";
     }
-    else {
+    else if (version.dwMajorVersion == 5) {
         switch (version.dwMinorVersion) {
           case 0:
             vendor_name = "Windows 2000";
@@ -2761,6 +2761,14 @@ int sigar_os_sys_info_get(sigar_t *sigar,
             break;
         }
     }
+    else if (version.dwMajorVersion == 6) {
+        switch (version.dwMinorVersion) {
+          default:
+            vendor_name = "Windows Vista";
+            vendor_version = "Vista";
+            break;
+        }
+    }
 
     SIGAR_SSTRCPY(sysinfo->name, "Win32");
     SIGAR_SSTRCPY(sysinfo->vendor, "Microsoft");