diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index 8b395b2a1596..f58bdf32668f 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -182,6 +182,7 @@ cpu_fork(td1, p2, td2, flags)
 	pcb2->pcb_ebx = (int)td2;		/* fork_trampoline argument */
 	pcb2->pcb_eip = (int)fork_trampoline;
 	pcb2->pcb_psl = td2->td_frame->tf_eflags & ~PSL_I; /* ints disabled */
+	pcb2->pcb_gs = rgs();
 	/*-
 	 * pcb2->pcb_dr*:	cloned above.
 	 * pcb2->pcb_savefpu:	cloned above.
@@ -358,6 +359,7 @@ cpu_set_upcall(struct thread *td, void *pcb)
 	pcb2->pcb_ebx = (int)td;			    /* trampoline arg */
 	pcb2->pcb_eip = (int)fork_trampoline;
 	pcb2->pcb_psl &= ~(PSL_I);	/* interrupts must be disabled */
+	pcb2->pcb_gs = rgs();
 	/*
 	 * If we didn't copy the pcb, we'd need to do the following registers:
 	 * pcb2->pcb_dr*:	cloned above.
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index 8b395b2a1596..f58bdf32668f 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -182,6 +182,7 @@ cpu_fork(td1, p2, td2, flags)
 	pcb2->pcb_ebx = (int)td2;		/* fork_trampoline argument */
 	pcb2->pcb_eip = (int)fork_trampoline;
 	pcb2->pcb_psl = td2->td_frame->tf_eflags & ~PSL_I; /* ints disabled */
+	pcb2->pcb_gs = rgs();
 	/*-
 	 * pcb2->pcb_dr*:	cloned above.
 	 * pcb2->pcb_savefpu:	cloned above.
@@ -358,6 +359,7 @@ cpu_set_upcall(struct thread *td, void *pcb)
 	pcb2->pcb_ebx = (int)td;			    /* trampoline arg */
 	pcb2->pcb_eip = (int)fork_trampoline;
 	pcb2->pcb_psl &= ~(PSL_I);	/* interrupts must be disabled */
+	pcb2->pcb_gs = rgs();
 	/*
 	 * If we didn't copy the pcb, we'd need to do the following registers:
 	 * pcb2->pcb_dr*:	cloned above.