--- ./src/cmd/ksh93/include/jobs.h.orig	2014-11-19 14:14:36.055335722 +0000
+++ ./src/cmd/ksh93/include/jobs.h	2014-11-19 14:16:12.275918218 +0000
@@ -33,6 +33,7 @@
 #   include	<signal.h>
 #endif /* !SIGINT */
 #include	"FEATURE/options"
+#include	<aso.h>
 
 #if SHOPT_COSHELL
 #   include	<coshell.h>
@@ -150,16 +151,13 @@ extern struct jobs job;
 #define vmbusy()	0
 #endif
 
-#define job_lock()	(job.in_critical++)
+#define job_lock()	asoincint(&job.in_critical)
 #define job_unlock()	\
 	do { \
 		int	_sig; \
-		if (!--job.in_critical && (_sig = job.savesig)) \
-		{ \
-			if (!job.in_critical++ && !vmbusy()) \
-				job_reap(_sig); \
-			job.in_critical--; \
-		} \
+		if (asogetint(&job.in_critical) == 1 && (_sig = job.savesig) && !vmbusy()) \
+		    job_reap(_sig); \
+		asodecint(&job.in_critical); \
 	} while(0)
 
 extern const char	e_jobusage[];