diff --git a/rtl/haiku/signal.inc b/rtl/haiku/signal.inc
index 5e6aa2999d..5526e6d504 100644
--- a/rtl/haiku/signal.inc
+++ b/rtl/haiku/signal.inc
@@ -283,8 +283,16 @@ type
   SignalRestorer  = Procedure;cdecl;
   PSignalRestorer = ^SignalRestorer;
   {$WARNING TODO : check with signal.h}
+  { Note: As of R1alpha3, sa_handler still was of SignalHandler type, with one one parameter,
+    but the Signal stack has a second parameter that is set to zero
+    and a third that is of type pvregs }
   sigActionHandler = procedure(Sig: Longint; SigContext: PSigContextRec; uContext : Pvregs);cdecl;
 
+  { Add those type definition to obtain same declaration as for other unix targets 
+    but do not forget the PSigInfo filed is currently nil for Haiku as of  R1alpha3 }
+  PSigInfo = PSigContextRec;
+  PSigContext = Pvregs;
+
   Sigset=sigset_t;
   TSigset=sigset_t;
   PSigSet = ^SigSet;