diff --git a/src/backend/port/win32/signal.c b/src/backend/port/win32/signal.c
index 36c6ebd..3724aa3 100644
--- a/src/backend/port/win32/signal.c
+++ b/src/backend/port/win32/signal.c
@@ -115,14 +115,14 @@ pgwin32_dispatch_queued_signals(void)
 
 		for (i = 0; i < PG_SIGNAL_COUNT; i++)
 		{
-			if (exec_mask & sigmask(i))
+			if (exec_mask & sigmask(i+1))
 			{
 				/* Execute this signal */
 				pqsigfunc	sig = pg_signal_array[i];
 
 				if (sig == SIG_DFL)
 					sig = pg_signal_defaults[i];
-				pg_signal_queue &= ~sigmask(i);
+				pg_signal_queue &= ~sigmask(i+1);
 				if (sig != SIG_ERR && sig != SIG_IGN && sig != SIG_DFL)
 				{
 					LeaveCriticalSection(&pg_signal_crit_sec);