diff --git a/psutil/_psutil_windows.c b/psutil/_psutil_windows.c
index 092b5af2f..a11d8c5c0 100644
--- a/psutil/_psutil_windows.c
+++ b/psutil/_psutil_windows.c
@@ -134,14 +134,12 @@ static PyObject *TimeoutAbandoned;
  */
 static PyObject *
 psutil_boot_time(PyObject *self, PyObject *args) {
-#if (_WIN32_WINNT >= 0x0600)  // Windows Vista
     ULONGLONG uptime;
-#else
-    double uptime;
-#endif
     time_t pt;
     FILETIME fileTime;
-    long long ll;
+    ULONGLONG ll;
+    HINSTANCE hKernel32;
+    psutil_GetTickCount64 = NULL;
 
     GetSystemTimeAsFileTime(&fileTime);
     /*
@@ -157,33 +155,26 @@ psutil_boot_time(PyObject *self, PyObject *args) {
     and 01-01-1601, from time_t the divide by 1e+7 to get to the same
     base granularity.
     */
-#if (_WIN32_WINNT >= 0x0600)  // Windows Vista
     ll = (((ULONGLONG)
-#else
-    ll = (((LONGLONG)
-#endif
         (fileTime.dwHighDateTime)) << 32) + fileTime.dwLowDateTime;
     pt = (time_t)((ll - 116444736000000000ull) / 10000000ull);
 
-    // GetTickCount64() is Windows Vista+ only. Dinamically load
-    // it at runtime. We may have used
+    // GetTickCount64() is Windows Vista+ only. Dynamically load
+    // GetTickCount64() at runtime. We may have used
     // "#if (_WIN32_WINNT >= 0x0600)" pre-processor but that way
     // the produced exe/wheels cannot be used on Windows XP, see:
     // https://github.com/giampaolo/psutil/issues/811#issuecomment-230639178
     if (psutil_GetTickCount64 != NULL) {
         // Windows >= Vista
-        uptime = psutil_GetTickCount64() / (ULONGLONG)1000.00f;
-        return Py_BuildValue("K", pt - uptime);
+        uptime = psutil_GetTickCount64() / 1000ull;
     }
     else {
         // Windows XP.
         // GetTickCount() time will wrap around to zero if the
         // system is run continuously for 49.7 days.
-        psutil_debug("Windows < Vista; using GetTickCount() instead of "
-                     "GetTickCount64()");
-        uptime = GetTickCount() / (LONGLONG)1000.00f;
-        return Py_BuildValue("L", pt - uptime);
+        uptime = (ULONGLONG)GetTickCount() / 1000ull;
     }
+    return Py_BuildValue("K", pt - uptime);
 }