--- rpl/src/instructions_s1.c	2013/12/03 09:36:14	1.70
+++ rpl/src/instructions_s1.c	2016/03/09 10:57:41	1.82
@@ -1,7 +1,7 @@
 /*
 ================================================================================
-  RPL/2 (R) version 4.1.17
-  Copyright (C) 1989-2013 Dr. BERTRAND Joël
+  RPL/2 (R) version 4.1.25
+  Copyright (C) 1989-2016 Dr. BERTRAND Joël
 
   This file is part of RPL/2.
 
@@ -3690,7 +3690,11 @@ instruction_syseval(struct_processus *s_
 
 		verrouillage_threads_concurrents(s_etat_processus);
 		pid = fork();
-		deverrouillage_threads_concurrents(s_etat_processus);
+
+		if (pid > 0)
+		{
+			deverrouillage_threads_concurrents(s_etat_processus);
+		}
 
 		if (pid < 0)
 		{