diff --git a/rtl/inc/system.inc b/rtl/inc/system.inc
index 7688d9ffa2..420d8bebb6 100644
--- a/rtl/inc/system.inc
+++ b/rtl/inc/system.inc
@@ -2415,7 +2415,7 @@ end;
 function AtomicDecrement (var Target: Cardinal) : Cardinal; {$ifdef SYSTEMINLINE}inline;{$endif}
 
 begin
-  Result:=Cardinal(InterlockedIncrement(Longint(Target)));
+  Result:=Cardinal(InterlockedDecrement(Longint(Target)));
 end;