diff --git a/sys/arch/sparc/sparc/process_machdep.c b/sys/arch/sparc/sparc/process_machdep.c
index 23d732219415..d9db825c2b57 100644
--- a/sys/arch/sparc/sparc/process_machdep.c
+++ b/sys/arch/sparc/sparc/process_machdep.c
@@ -122,6 +122,9 @@ process_write_regs(struct lwp *l, const struct reg *regs)
 {
 	int	psr = l->l_md.md_tf->tf_psr & ~PSR_ICC;
 
+	if (((regs->r_pc | regs->r_npc) & 0x03) != 0)
+		return EINVAL;
+
 	memcpy(l->l_md.md_tf, regs, sizeof(*regs));
 	l->l_md.md_tf->tf_psr = psr | (regs->r_psr & PSR_ICC);
 	return 0;
@@ -140,6 +143,9 @@ int
 process_set_pc(struct lwp *l, void *addr)
 {
 
+	if (((u_int)addr & 0x03) != 0)
+		return EINVAL;
+
 	l->l_md.md_tf->tf_pc = (u_int)addr;
 	l->l_md.md_tf->tf_npc = (u_int)addr + 4;
 	return 0;