diff --git a/Cargo.lock b/Cargo.lock
index feb2d88..4173ba7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,6 +4,7 @@
 name = "adc2tcp"
 version = "0.0.0"
 dependencies = [
+ "bare-metal 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "cortex-m 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "cortex-m-log 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "cortex-m-rt 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/Cargo.toml b/Cargo.toml
index 7839098..1eb40b6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,6 +22,7 @@ default-target = "thumbv7em-none-eabihf"
 panic-abort = { version = "0.3.1" }
 panic-semihosting = { version = "0.5.1", optional = true }
 log = "0.4"
+bare-metal = "0.2"
 cortex-m = "0.5"
 cortex-m-rt = { version = "0.6", features = ["device"] }
 cortex-m-log = { version = "0.4", features = ["log-integration"] }
diff --git a/src/main.rs b/src/main.rs
index 8b6e625..a66260b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -122,14 +122,16 @@ fn main() -> ! {
 
             // Update watchdog
             wd.feed();
-            led_red.off();
 
-            // Wait for interrupts
-            // if net.is_pending() {
-                led_green.on();
-                wfi();
-                led_green.off();
-            // }
+            led_red.on();
+            cortex_m::interrupt::free(|cs| {
+                if !net::is_pending(cs) {
+                    // Wait for interrupts
+                    wfi();
+                    net::clear_pending(cs);
+                }
+            });
+            led_red.off();
         }
     })
 }
diff --git a/src/net.rs b/src/net.rs
index 0397056..9196de2 100644
--- a/src/net.rs
+++ b/src/net.rs
@@ -1,6 +1,9 @@
 //! As there is only one peripheral, supporting data structures are
 //! declared once and globally.
 
+use core::cell::RefCell;
+use cortex_m::interrupt::Mutex;
+use bare_metal::CriticalSection;
 use stm32f4xx_hal::{
     stm32::{interrupt, Peripherals, NVIC, ETHERNET_MAC, ETHERNET_DMA},
 };
@@ -17,6 +20,7 @@ static mut TX_RING: Option<[RingEntry<TxDescriptor>; 2]> = None;
 // TODO: generate one from device id
 const SRC_MAC: [u8; 6] = [0x00, 0x00, 0xDE, 0xAD, 0xBE, 0xEF];
 
+static NET_PENDING: Mutex<RefCell<bool>> = Mutex::new(RefCell::new(false));
 
 pub fn run<F>(nvic: &mut NVIC, ethernet_mac: ETHERNET_MAC, ethernet_dma: ETHERNET_DMA, f: F) -> !
 where
@@ -79,6 +83,21 @@ impl<'a> NetInterface<'a> {
 /// and TODO: set pending flag
 #[interrupt]
 fn ETH() {
+    cortex_m::interrupt::free(|cs| {
+        *NET_PENDING.borrow(cs)
+            .borrow_mut() = true;
+    });
+
     let p = unsafe { Peripherals::steal() };
     stm32_eth::eth_interrupt_handler(&p.ETHERNET_DMA);
 }
+
+pub fn is_pending(cs: &CriticalSection) -> bool {
+    *NET_PENDING.borrow(cs)
+        .borrow()
+}
+
+pub fn clear_pending(cs: &CriticalSection) {
+    *NET_PENDING.borrow(cs)
+        .borrow_mut() = false;
+}