diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 46b520030dc..445582a176c 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -2648,7 +2648,9 @@ ptracestop(struct thread *td, int sig, ksiginfo_t *si)
 				td->td_dbgflags &= ~TDB_STOPATFORK;
 			}
 stopme:
+			td->td_dbgflags |= TDB_SSWITCH;
 			thread_suspend_switch(td, p);
+			td->td_dbgflags &= ~TDB_SSWITCH;
 			if (p->p_xthread == td)
 				p->p_xthread = NULL;
 			if (!(p->p_flag & P_TRACED))
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index e02e97d7422..b959681e992 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -485,6 +485,7 @@ do {									\
 #define	TDB_VFORK	0x00000800 /* vfork indicator for ptrace() */
 #define	TDB_FSTP	0x00001000 /* The thread is PT_ATTACH leader */
 #define	TDB_STEP	0x00002000 /* (x86) PSL_T set for PT_STEP */
+#define	TDB_SSWITCH	0x00004000 /* Suspended in ptracestop */
 
 /*
  * "Private" flags kept in td_pflags: