diff --git a/kernel/src/arch/riscv/irq.rs b/kernel/src/arch/riscv/irq.rs
index 28961081d..7958908e2 100644
--- a/kernel/src/arch/riscv/irq.rs
+++ b/kernel/src/arch/riscv/irq.rs
@@ -18,14 +18,17 @@ extern "C" {
     fn flush_mmu();
 }
 
+// use RAM-based backing so this variable is automatically saved on suspend
+static mut SIM_BACKING: usize = 0;
 /// Disable external interrupts
 pub fn disable_all_irqs() {
-    unsafe { sie::clear_sext() };
+    unsafe{SIM_BACKING = sim::read()};
+    sim::write(0x0);
 }
 
 /// Enable external interrupts
 pub fn enable_all_irqs() {
-    unsafe { sie::set_sext() };
+    sim::write(unsafe{SIM_BACKING});
 }
 
 pub fn enable_irq(irq_no: usize) {