diff --git a/ports/litex/boards/fomu/fomu-spi.ld b/ports/litex/boards/fomu/fomu-spi.ld
index 9b6443c673..e7db25b0c5 100644
--- a/ports/litex/boards/fomu/fomu-spi.ld
+++ b/ports/litex/boards/fomu/fomu-spi.ld
@@ -51,6 +51,11 @@ SECTIONS
         *(.text.tu_edpt_dir)
         *(.text.tu_fifo_empty)
         *(.text.usbd_edpt_busy)
+        *(.text.usb_irq_handler)
+        *(.text.supervisor_tick)
+        *(.text.port_get_raw_ticks)
+        *(.text.__modsi3)
+        *(.text.__udivsi3)
         *(.text.irq_getmask)
         *(.text.irq_setmask)
         *(.text.irq_pending)
diff --git a/ports/litex/common-hal/microcontroller/__init__.c b/ports/litex/common-hal/microcontroller/__init__.c
index 3c91661144..522a41e2e3 100644
--- a/ports/litex/common-hal/microcontroller/__init__.c
+++ b/ports/litex/common-hal/microcontroller/__init__.c
@@ -59,12 +59,15 @@ void common_hal_mcu_delay_us(uint32_t delay) {
 
 volatile uint32_t nesting_count = 0;
 
+__attribute__((section(".ramtext")))
 void common_hal_mcu_disable_interrupts(void) {
-    irq_setie(0);
-    // __DMB();
+    if (nesting_count == 0) {
+        irq_setie(0);
+    }
     nesting_count++;
 }
 
+__attribute__((section(".ramtext")))
 void common_hal_mcu_enable_interrupts(void) {
     if (nesting_count == 0) {
         // This is very very bad because it means there was mismatched disable/enables so we