diff --git a/src/core/pitime.cpp b/src/core/pitime.cpp
index 58e9212d..8ee6cb3e 100755
--- a/src/core/pitime.cpp
+++ b/src/core/pitime.cpp
@@ -232,10 +232,10 @@ PISystemTime PISystemTime::current(bool precise_but_not_system) {
 #  endif
 		sft.dwHighDateTime = ft.dwHighDateTime - __pi_ftjan1970.dwHighDateTime;
 		if (ft.dwLowDateTime < __pi_ftjan1970.dwLowDateTime) {
-			sft.dwLowDateTime += (0xFFFFFFFF - __pi_ftjan1970.dwLowDateTime);
+			sft.dwLowDateTime = ft.dwLowDateTime + (0xFFFFFFFF - __pi_ftjan1970.dwLowDateTime);
 			sft.dwHighDateTime--;
 		} else
-			sft.dwLowDateTime -= __pi_ftjan1970.dwLowDateTime;
+			sft.dwLowDateTime = ft.dwLowDateTime - __pi_ftjan1970.dwLowDateTime;
 		ullong lt = ullong(sft.dwHighDateTime) * 0x100000000U + ullong(sft.dwLowDateTime);
 		return PISystemTime(lt / 10000000U, (lt % 10000000U) * 100U);
 	}