diff --git a/sys/i386/i386/exec_machdep.c b/sys/i386/i386/exec_machdep.c
index 29c06ff86ca8..45921193ec94 100644
--- a/sys/i386/i386/exec_machdep.c
+++ b/sys/i386/i386/exec_machdep.c
@@ -640,6 +640,7 @@ osigreturn(struct thread *td, struct osigreturn_args *uap)
 	regs->tf_esp = scp->sc_sp;
 	regs->tf_eip = scp->sc_pc;
 	regs->tf_eflags = eflags;
+	regs->tf_trapno = T_RESERVED;
 
 #if defined(COMPAT_43)
 	if (scp->sc_onstack & 1)
@@ -739,6 +740,7 @@ freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
 
 		bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
 	}
+	regs->tf_trapno = T_RESERVED;
 
 #if defined(COMPAT_43)
 	if (ucp->uc_mcontext.mc_onstack & 1)
@@ -873,6 +875,7 @@ sys_sigreturn(struct thread *td, struct sigreturn_args *uap)
 			return (ret);
 		bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
 	}
+	regs->tf_trapno = T_RESERVED;
 
 #if defined(COMPAT_43)
 	if (ucp->uc_mcontext.mc_onstack & 1)