diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -229,6 +229,14 @@
 
 	copy_thread(td1, td2);
 
+	/* Reset debug registers in the new process */
+	pcb2->pcb_dr0 = 0;
+	pcb2->pcb_dr1 = 0;
+	pcb2->pcb_dr2 = 0;
+	pcb2->pcb_dr3 = 0;
+	pcb2->pcb_dr6 = 0;
+	pcb2->pcb_dr7 = 0;
+
 	/* Point mdproc and then copy over p1's contents */
 	mdp2 = &p2->p_md;
 	bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -241,6 +241,14 @@
 
 	copy_thread(td1, td2);
 
+	/* Reset debug registers in the new process */
+	pcb2->pcb_dr0 = 0;
+	pcb2->pcb_dr1 = 0;
+	pcb2->pcb_dr2 = 0;
+	pcb2->pcb_dr3 = 0;
+	pcb2->pcb_dr6 = 0;
+	pcb2->pcb_dr7 = 0;
+
 	/* Point mdproc and then copy over td1's contents */
 	mdp2 = &p2->p_md;
 	bcopy(&p1->p_md, mdp2, sizeof(*mdp2));