diff --git a/sys/amd64/amd64/fpu.c b/sys/amd64/amd64/fpu.c
index 06a7d5df9d75..513b36b7d0b0 100644
--- a/sys/amd64/amd64/fpu.c
+++ b/sys/amd64/amd64/fpu.c
@@ -125,6 +125,10 @@ fpuinit(void)
 	mxcsr = __INITIAL_MXCSR__;
 	ldmxcsr(mxcsr);
 	fxsave(&fpu_cleanstate);
+	if (fpu_cleanstate.sv_env.en_mxcsr_mask)
+		cpu_mxcsr_mask = fpu_cleanstate.sv_env.en_mxcsr_mask;
+	else
+		cpu_mxcsr_mask = 0xFFBF;
 	start_emulating();
 	bzero(fpu_cleanstate.sv_fp, sizeof(fpu_cleanstate.sv_fp));
 	bzero(fpu_cleanstate.sv_xmm, sizeof(fpu_cleanstate.sv_xmm));
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 026046218937..43c19d39e0ca 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -1507,7 +1507,7 @@ set_fpregs_xmm(struct fpreg *fpregs, struct savefpu *sv_xmm)
 	penv_xmm->en_rip = penv_fpreg->en_rip;
 	penv_xmm->en_rdp = penv_fpreg->en_rdp;
 	penv_xmm->en_mxcsr = penv_fpreg->en_mxcsr;
-	penv_xmm->en_mxcsr_mask = penv_fpreg->en_mxcsr_mask;
+	penv_xmm->en_mxcsr_mask = penv_fpreg->en_mxcsr_mask & cpu_mxcsr_mask;
 
 	/* FPU registers */
 	for (i = 0; i < 8; ++i)
@@ -1634,6 +1634,7 @@ get_fpcontext(struct thread *td, mcontext_t *mcp)
 static int
 set_fpcontext(struct thread *td, const mcontext_t *mcp)
 {
+	struct savefpu *fpstate;
 
 	if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
 		return (0);
@@ -1649,7 +1650,9 @@ set_fpcontext(struct thread *td, const mcontext_t *mcp)
 		 * be called with interrupts disabled.
 		 * XXX obsolete on trap-16 systems?
 		 */
-		fpusetregs(td, (struct savefpu *)&mcp->mc_fpstate);
+		fpstate = (struct savefpu *)&mcp->mc_fpstate;
+		fpstate->sv_env.en_mxcsr &= cpu_mxcsr_mask;
+		fpusetregs(td, fpstate);
 	} else
 		return (EINVAL);
 	return (0);
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index 4e421eea1654..03220e6a0640 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -47,6 +47,7 @@ extern	u_int	amd_feature2;
 extern	u_int	cpu_fxsr;
 extern	u_int	cpu_high;
 extern	u_int	cpu_id;
+extern	u_int	cpu_mxcsr_mask;
 extern	u_int	cpu_procinfo;
 extern	u_int	cpu_procinfo2;
 extern	char	cpu_vendor[];