diff --git a/sim/src/image.rs b/sim/src/image.rs
index 988d136..5898560 100644
--- a/sim/src/image.rs
+++ b/sim/src/image.rs
@@ -428,8 +428,7 @@
         if Caps::Bootstrap.present() {
             info!("Try bootstraping image in the primary");
 
-            let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-            if result != 0 {
+            if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
                 warn!("Failed first boot");
                 fails += 1;
             }
@@ -598,8 +597,7 @@
         info!("Try norevert");
 
         // First do a normal upgrade...
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed first boot");
             fails += 1;
         }
@@ -632,8 +630,7 @@
             fails += 1;
         }
 
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed second boot");
             fails += 1;
         }
@@ -668,8 +665,7 @@
         info!("Try no downgrade");
 
         // First, do a normal upgrade.
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed first boot");
             fails += 1;
         }
@@ -706,8 +702,7 @@
         }
 
         // Run the bootloader...
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed first boot");
             fails += 1;
         }
@@ -755,8 +750,7 @@
         }
 
         // Run the bootloader...
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed first boot");
             fails += 1;
         }
@@ -792,8 +786,7 @@
         self.mark_upgrades(&mut flash, 1);
 
         // Run the bootloader...
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed first boot");
             fails += 1;
         }
@@ -840,15 +833,15 @@
         self.mark_permanent_upgrades(&mut flash, 1);
         self.mark_bad_status_with_rate(&mut flash, 0, 1.0);
 
-        let (result, asserts) = c::boot_go(&mut flash, &self.areadesc, None, true);
-        if result != 0 {
+        let result = c::boot_go(&mut flash, &self.areadesc, None, true);
+        if !result.success() {
             warn!("Failed!");
             fails += 1;
         }
 
         // Failed writes to the marked "bad" region don't assert anymore.
         // Any detected assert() is happening in another part of the code.
-        if asserts != 0 {
+        if result.asserts() != 0 {
             warn!("At least one assert() was called");
             fails += 1;
         }
@@ -866,8 +859,7 @@
 
         info!("validate primary slot enabled; \
                re-run of boot_go should just work");
-        let (result, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if result != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Failed!");
             fails += 1;
         }
@@ -899,7 +891,7 @@
             self.mark_bad_status_with_rate(&mut flash, 0, 0.5);
 
             // Should not fail, writing to bad regions does not assert
-            let (_, asserts) = c::boot_go(&mut flash, &self.areadesc, Some(&mut count), true);
+            let asserts = c::boot_go(&mut flash, &self.areadesc, Some(&mut count), true).asserts();
             if asserts != 0 {
                 warn!("At least one assert() was called");
                 fails += 1;
@@ -908,7 +900,7 @@
             self.reset_bad_status(&mut flash, 0);
 
             info!("Resuming an interrupted swap operation");
-            let (_, asserts) = c::boot_go(&mut flash, &self.areadesc, None, true);
+            let asserts = c::boot_go(&mut flash, &self.areadesc, None, true).asserts();
 
             // This might throw no asserts, for large sector devices, where
             // a single failure writing is indistinguishable from no failure,
@@ -935,7 +927,7 @@
             self.mark_bad_status_with_rate(&mut flash, 0, 1.0);
 
             // This is expected to fail while writing to bad regions...
-            let (_, asserts) = c::boot_go(&mut flash, &self.areadesc, None, true);
+            let asserts = c::boot_go(&mut flash, &self.areadesc, None, true).asserts();
             if asserts == 0 {
                 warn!("No assert() detected");
                 fails += 1;
@@ -995,18 +987,18 @@
         let mut counter = stop.unwrap_or(0);
 
         let (first_interrupted, count) = match c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false) {
-            (-0x13579, _) => (true, stop.unwrap()),
-            (0, _) => (false, -counter),
-            (x, _) => panic!("Unknown return: {}", x),
+            x if x.interrupted() => (true, stop.unwrap()),
+            x if x.success() => (false, -counter),
+            x => panic!("Unknown return: {:?}", x),
         };
 
         counter = 0;
         if first_interrupted {
             // fl.dump();
             match c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false) {
-                (-0x13579, _) => panic!("Shouldn't stop again"),
-                (0, _) => (),
-                (x, _) => panic!("Unknown return: {}", x),
+                x if x.interrupted() => panic!("Shouldn't stop again"),
+                x if x.success() => (),
+                x => panic!("Unknown return: {:?}", x),
             }
         }
 
@@ -1019,7 +1011,7 @@
         // fl.write_file("image0.bin").unwrap();
         for i in 0 .. count {
             info!("Running boot pass {}", i + 1);
-            assert_eq!(c::boot_go(&mut flash, &self.areadesc, None, false), (0, 0));
+            assert!(c::boot_go(&mut flash, &self.areadesc, None, false).success_no_asserts());
         }
         flash
     }
@@ -1029,8 +1021,7 @@
         let mut fails = 0;
 
         let mut counter = stop;
-        let (x, _) = c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false);
-        if x != -0x13579 {
+        if !c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false).interrupted() {
             warn!("Should have stopped test at interruption point");
             fails += 1;
         }
@@ -1042,8 +1033,7 @@
             fails += 1;
         }
 
-        let (x, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if x != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Should have finished test upgrade");
             fails += 1;
         }
@@ -1071,14 +1061,12 @@
 
         // Do Revert
         let mut counter = stop;
-        let (x, _) = c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false);
-        if x != -0x13579 {
+        if !c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false).interrupted() {
             warn!("Should have stopped revert at interruption point");
             fails += 1;
         }
 
-        let (x, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if x != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Should have finished revert upgrade");
             fails += 1;
         }
@@ -1105,8 +1093,7 @@
             fails += 1;
         }
 
-        let (x, _) = c::boot_go(&mut flash, &self.areadesc, None, false);
-        if x != 0 {
+        if !c::boot_go(&mut flash, &self.areadesc, None, false).success() {
             warn!("Should have finished 3rd boot");
             fails += 1;
         }
@@ -1136,17 +1123,17 @@
             let reset_counter = rng.gen_range(1, remaining_ops / 2);
             let mut counter = reset_counter;
             match c::boot_go(&mut flash, &self.areadesc, Some(&mut counter), false) {
-                (0, _) | (-0x13579, _) => (),
-                (x, _) => panic!("Unknown return: {}", x),
+                x if x.interrupted() => (),
+                x => panic!("Unknown return: {:?}", x),
             }
             remaining_ops -= reset_counter;
             *reset = reset_counter;
         }
 
         match c::boot_go(&mut flash, &self.areadesc, None, false) {
-            (-0x13579, _) => panic!("Should not be have been interrupted!"),
-            (0, _) => (),
-            (x, _) => panic!("Unknown return: {}", x),
+            x if x.interrupted() => panic!("Should not be have been interrupted!"),
+            x if x.success() => (),
+            x => panic!("Unknown return: {:?}", x),
         }
 
         (flash, resets)