diff --git a/sim/src/image.rs b/sim/src/image.rs
index 4a39010..e9865e4 100644
--- a/sim/src/image.rs
+++ b/sim/src/image.rs
@@ -325,6 +325,19 @@
                 flash.insert(dev_id, dev);
                 (flash, areadesc, &[])
             }
+            DeviceName::Nrf52840UnequalSlots => {
+                let dev = SimFlash::new(vec![4096; 128], align as usize, erased_val);
+
+                let dev_id = 0;
+                let mut areadesc = AreaDesc::new();
+                areadesc.add_flash_sectors(dev_id, &dev);
+                areadesc.add_image(0x008000, 0x03c000, FlashId::Image0, dev_id);
+                areadesc.add_image(0x044000, 0x03b000, FlashId::Image1, dev_id);
+
+                let mut flash = SimMultiFlash::new();
+                flash.insert(dev_id, dev);
+                (flash, areadesc, &[Caps::SwapUsingScratch, Caps::OverwriteUpgrade])
+            }
             DeviceName::Nrf52840SpiFlash => {
                 // Simulate nrf52840 with external SPI flash. The external SPI flash
                 // has a larger sector size so for now store scratch on that flash.
diff --git a/sim/src/lib.rs b/sim/src/lib.rs
index ec8e5ed..93cdbfa 100644
--- a/sim/src/lib.rs
+++ b/sim/src/lib.rs
@@ -62,7 +62,10 @@
 }
 
 #[derive(Copy, Clone, Debug, Deserialize)]
-pub enum DeviceName { Stm32f4, K64f, K64fBig, K64fMulti, Nrf52840, Nrf52840SpiFlash, }
+pub enum DeviceName {
+    Stm32f4, K64f, K64fBig, K64fMulti, Nrf52840, Nrf52840SpiFlash,
+    Nrf52840UnequalSlots,
+}
 
 pub static ALL_DEVICES: &'static [DeviceName] = &[
     DeviceName::Stm32f4,
@@ -71,6 +74,7 @@
     DeviceName::K64fMulti,
     DeviceName::Nrf52840,
     DeviceName::Nrf52840SpiFlash,
+    DeviceName::Nrf52840UnequalSlots,
 ];
 
 impl fmt::Display for DeviceName {
@@ -82,6 +86,7 @@
             DeviceName::K64fMulti => "k64fmulti",
             DeviceName::Nrf52840 => "nrf52840",
             DeviceName::Nrf52840SpiFlash => "Nrf52840SpiFlash",
+            DeviceName::Nrf52840UnequalSlots => "Nrf52840UnequalSlots",
         };
         f.write_str(name)
     }