diff --git a/lib/connect.c b/lib/connect.c
index ac2f26833..dcfb4b469 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -72,6 +72,7 @@
 #include "warnless.h"
 #include "conncache.h"
 #include "multihandle.h"
+#include "system_win32.h"
 
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
@@ -945,44 +946,15 @@ void Curl_sndbufset(curl_socket_t sockfd)
   int val = CURL_MAX_WRITE_SIZE + 32;
   int curval = 0;
   int curlen = sizeof(curval);
-  DWORD majorVersion = 6;
 
   static int detectOsState = DETECT_OS_NONE;
 
-  if(detectOsState == DETECT_OS_NONE) {
-#if !defined(_WIN32_WINNT) || !defined(_WIN32_WINNT_WIN2K) || \
-    (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
-    OSVERSIONINFO osver;
-
-    memset(&osver, 0, sizeof(osver));
-    osver.dwOSVersionInfoSize = sizeof(osver);
-
-    detectOsState = DETECT_OS_PREVISTA;
-    if(GetVersionEx(&osver)) {
-      if(osver.dwMajorVersion >= majorVersion)
-        detectOsState = DETECT_OS_VISTA_OR_LATER;
-    }
-#else
-    ULONGLONG cm;
-    OSVERSIONINFOEX osver;
-
-    memset(&osver, 0, sizeof(osver));
-    osver.dwOSVersionInfoSize = sizeof(osver);
-    osver.dwMajorVersion = majorVersion;
-
-    cm = VerSetConditionMask(0, VER_MAJORVERSION, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_MINORVERSION, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_SERVICEPACKMAJOR, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_SERVICEPACKMINOR, VER_GREATER_EQUAL);
-
-    if(VerifyVersionInfo(&osver, (VER_MAJORVERSION | VER_MINORVERSION |
-                                  VER_SERVICEPACKMAJOR | VER_SERVICEPACKMINOR),
-                         cm))
+  if(detectOsState == DETECT_OS_NONE)
+    if(Curl_verify_windows_version(6, 0, PLATFORM_WINNT,
+                                   VERSION_GREATER_THAN_EQUAL))
       detectOsState = DETECT_OS_VISTA_OR_LATER;
     else
       detectOsState = DETECT_OS_PREVISTA;
-#endif
-  }
 
   if(detectOsState == DETECT_OS_VISTA_OR_LATER)
     return;
diff --git a/lib/curl_sspi.c b/lib/curl_sspi.c
index 54bbef6f6..ee3f1b1c1 100644
--- a/lib/curl_sspi.c
+++ b/lib/curl_sspi.c
@@ -67,7 +67,6 @@ PSecurityFunctionTable s_pSecFn = NULL;
  */
 CURLcode Curl_sspi_global_init(void)
 {
-  bool securityDll = FALSE;
   INITSECURITYINTERFACE_FN pInitSecurityInterface;
 
   /* If security interface is not yet initialized try to do this */
@@ -75,49 +74,9 @@ CURLcode Curl_sspi_global_init(void)
     /* Security Service Provider Interface (SSPI) functions are located in
      * security.dll on WinNT 4.0 and in secur32.dll on Win9x. Win2K and XP
      * have both these DLLs (security.dll forwards calls to secur32.dll) */
-    DWORD majorVersion = 4;
-    DWORD platformId = VER_PLATFORM_WIN32_NT;
-
-#if !defined(_WIN32_WINNT) || !defined(_WIN32_WINNT_WIN2K) || \
-    (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
-    OSVERSIONINFO osver;
-
-    memset(&osver, 0, sizeof(osver));
-    osver.dwOSVersionInfoSize = sizeof(osver);
-
-    /* Find out Windows version */
-    if(!GetVersionEx(&osver))
-      return CURLE_FAILED_INIT;
-
-    /* Verify the major version number == 4 and platform id == WIN_NT */
-    if(osver.dwMajorVersion == majorVersion &&
-       osver.dwPlatformId == platformId)
-      securityDll = TRUE;
-#else
-    ULONGLONG cm;
-    OSVERSIONINFOEX osver;
-
-    memset(&osver, 0, sizeof(osver));
-    osver.dwOSVersionInfoSize = sizeof(osver);
-    osver.dwMajorVersion = majorVersion;
-    osver.dwPlatformId = platformId;
-
-    cm = VerSetConditionMask(0, VER_MAJORVERSION, VER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_MINORVERSION, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_SERVICEPACKMAJOR, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_SERVICEPACKMINOR, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_PLATFORMID, VER_EQUAL);
-
-    /* Verify the major version number == 4 and platform id == WIN_NT */
-    if(VerifyVersionInfo(&osver, (VER_MAJORVERSION | VER_MINORVERSION |
-                                  VER_SERVICEPACKMAJOR | VER_SERVICEPACKMINOR |
-                                  VER_PLATFORMID),
-                         cm))
-      securityDll = TRUE;
-#endif
 
     /* Load SSPI dll into the address space of the calling process */
-    if(securityDll)
+    if(Curl_verify_windows_version(4, 0, PLATFORM_WINNT, VERSION_EQUAL))
       s_hSecDll = Curl_load_library(TEXT("security.dll"));
     else
       s_hSecDll = Curl_load_library(TEXT("secur32.dll"));
diff --git a/lib/vtls/schannel.c b/lib/vtls/schannel.c
index 38a2aa33e..23019f812 100644
--- a/lib/vtls/schannel.c
+++ b/lib/vtls/schannel.c
@@ -58,8 +58,10 @@
 #include "warnless.h"
 #include "x509asn1.h"
 #include "curl_printf.h"
+#include "system_win32.h"
+
+ /* The last #include file should be: */
 #include "curl_memory.h"
-/* The last #include file should be: */
 #include "memdebug.h"
 
 /* ALPN requires version 8.1 of the  Windows SDK, which was
@@ -1261,39 +1263,8 @@ cleanup:
   */
   if(len && !connssl->decdata_offset && connssl->recv_connection_closed &&
      !connssl->recv_sspi_close_notify) {
-    bool isWin2k = FALSE;
-
-#if !defined(_WIN32_WINNT) || !defined(_WIN32_WINNT_WIN2K) || \
-    (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
-    OSVERSIONINFO osver;
-
-    memset(&osver, 0, sizeof(osver));
-    osver.dwOSVersionInfoSize = sizeof(osver);
-
-    /* Find out the Windows version */
-    if(GetVersionEx(&osver)) {
-      /* Verify the version number is 5.0 */
-      if(osver.dwMajorVersion == 5 && osver.dwMinorVersion == 0)
-        isWin2k = TRUE;
-    }
-#else
-    ULONGLONG cm;
-    OSVERSIONINFOEX osver;
-
-    memset(&osver, 0, sizeof(osver));
-    osver.dwOSVersionInfoSize = sizeof(osver);
-    osver.dwMajorVersion = 5;
-
-    cm = VerSetConditionMask(0, VER_MAJORVERSION, VER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_MINORVERSION, VER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_SERVICEPACKMAJOR, VER_GREATER_EQUAL);
-    cm = VerSetConditionMask(cm, VER_SERVICEPACKMINOR, VER_GREATER_EQUAL);
-
-    if(VerifyVersionInfo(&osver, (VER_MAJORVERSION | VER_MINORVERSION |
-                                  VER_SERVICEPACKMAJOR | VER_SERVICEPACKMINOR),
-                         cm))
-      isWin2k = TRUE;
-#endif
+    bool isWin2k = Curl_verify_windows_version(5, 0, PLATFORM_WINNT,
+                                               VERSION_EQUAL);
 
     if(isWin2k && sspi_status == SEC_E_OK)
       connssl->recv_sspi_close_notify = true;