diff --git a/dlls/kernel/time.c b/dlls/kernel/time.c
index 9e38622..89db60e 100644
--- a/dlls/kernel/time.c
+++ b/dlls/kernel/time.c
@@ -518,8 +518,9 @@ VOID WINAPI GetSystemTimeAsFileTime(
  */
 static void TIME_ClockTimeToFileTime(clock_t unix_time, LPFILETIME filetime)
 {
+    long clocksPerSec = sysconf(_SC_CLK_TCK);
     ULONGLONG secs = RtlEnlargedUnsignedMultiply( unix_time, 10000000 );
-    secs = RtlExtendedLargeIntegerDivide( secs, CLK_TCK, NULL );
+    secs = RtlExtendedLargeIntegerDivide( secs, clocksPerSec, NULL );
     filetime->dwLowDateTime  = (DWORD)secs;
     filetime->dwHighDateTime = (DWORD)(secs >> 32);
 }