diff --git a/raven_spn/raven_spn b/raven_spn/raven_spn
index b473534..c363555 100755
Binary files a/raven_spn/raven_spn and b/raven_spn/raven_spn differ
diff --git a/raven_spn/src/init.h b/raven_spn/src/init.h
index fa4d3e7..0e10921 100644
--- a/raven_spn/src/init.h
+++ b/raven_spn/src/init.h
@@ -12,8 +12,8 @@ typedef void (*function_ptr_t) (void);
 //! Instance data for the PLIC.
 plic_instance_t g_plic;
 std::array<function_ptr_t,PLIC_NUM_INTERRUPTS>  g_ext_interrupt_handlers;
-bool spn1_hw_interrupt{true};
-bool spn2_hw_interrupt{true};
+volatile bool spn1_hw_interrupt{true};
+volatile bool spn2_hw_interrupt{true};
 
 
 /*! \brief external interrupt handler
@@ -45,36 +45,40 @@ void configure_irq(size_t irq_num, function_ptr_t handler, unsigned char prio=1)
 }
 
 void wait_for_spn1_interrupt() {
-    // wait until HW is done
-    if(spn1_hw_interrupt) {
-        do{
-            asm("wfi");
-            asm("nop");
-        }while(spn1_hw_interrupt);
+    clear_csr(mie, MIP_MEIP);
+    while(spn1_hw_interrupt) {
+        set_csr(mie, MIP_MEIP);
+        asm("wfi");
+        clear_csr(mie, MIP_MEIP);
+        asm("nop");
     }
 	spn1_hw_interrupt=true;
+    set_csr(mie, MIP_MEIP);
 }
 
 void wait_for_spn2_interrupt() {
-    // wait until HW is done
-    if(spn2_hw_interrupt) {
-        do{
-            asm("wfi");
-            asm("nop");
-        }while(spn2_hw_interrupt);
+    clear_csr(mie, MIP_MEIP);
+    while(spn2_hw_interrupt) {
+        set_csr(mie, MIP_MEIP);
+        asm("wfi");
+        clear_csr(mie, MIP_MEIP);
+        asm("nop");
     }
     spn2_hw_interrupt=true;
+    set_csr(mie, MIP_MEIP);
 }
 
 void wait_for_spn_interrupts() {
-    if(spn1_hw_interrupt || spn2_hw_interrupt) {
-        do{
-            asm("wfi");
-            asm("nop");
-        }while(spn1_hw_interrupt || spn2_hw_interrupt);
+    clear_csr(mie, MIP_MEIP);
+    while(spn1_hw_interrupt || spn2_hw_interrupt) {
+        set_csr(mie, MIP_MEIP);
+        asm("wfi");
+        asm("nop");
+        clear_csr(mie, MIP_MEIP);
     }
     spn1_hw_interrupt=true;
     spn2_hw_interrupt=true;
+    set_csr(mie, MIP_MEIP);
 }
 
 /*!\brief initializes platform