diff --git a/pallets/acurast/common/src/tests.rs b/pallets/acurast/common/src/tests.rs
index f58b7717..71d94eaf 100644
--- a/pallets/acurast/common/src/tests.rs
+++ b/pallets/acurast/common/src/tests.rs
@@ -311,6 +311,24 @@ tests! {
             0,
             vec![((0,1), true), ((8,10), false)]
         );
+        //  ╭start ╭end
+        // _■■■■■■■■
+        // ranges:
+        // ■
+        // ■■
+        // ■■■■■■■■■■
+        //          ■■
+        test_schedule_overlaps_start(
+            Schedule{
+                duration: 2,
+                start_time: 1,
+                end_time: 9,
+                interval: 2,
+                max_start_delay: 0,
+            },
+            0,
+            vec![((0,1), false), ((0,2), true), ((0, 10), true), ((8, 10), true), ((9, 10), false)]
+        );
         // ╭start         ╭end
         // ■■___■■___■■___
         //      ■■
@@ -346,5 +364,27 @@ tests! {
             2,
             vec![((0,3), false), ((2,4), false), ((10,12), true), ((12,15), false)]
         );
+        test_schedule_overlaps_end_before_start(
+            Schedule{
+                duration: 2,
+                start_time: 1,
+                end_time: 0,
+                interval: 2,
+                max_start_delay: 0,
+            },
+            0,
+            vec![((0,1), false), ((0,2), false)]
+        );
+        test_schedule_overlaps_equal_start_end(
+            Schedule{
+                duration: 2,
+                start_time: 0,
+                end_time: 0,
+                interval: 2,
+                max_start_delay: 0,
+            },
+            0,
+            vec![((0,1), false), ((0,2), false)]
+        );
     }
 }
diff --git a/pallets/acurast/common/src/types.rs b/pallets/acurast/common/src/types.rs
index c7b55552..f864ab8b 100644
--- a/pallets/acurast/common/src/types.rs
+++ b/pallets/acurast/common/src/types.rs
@@ -153,23 +153,25 @@ impl Schedule {
 
     pub fn overlaps(&self, start_delay: u64, a: u64, b: u64) -> Option<bool> {
         let (start, end) = self.range(start_delay)?;
-        if a == b || start == end || b <= start || a >= end {
+        if b <= a || start == end || b <= start || end <= a {
             return Some(false);
         }
 
         // if query interval `[a, b]` starts before, we can pretend it only starts at `start`
-        let relative_a = a.checked_sub(start).or(Some(start))?;
+        let relative_a = a.checked_sub(start).unwrap_or(start);
 
         if let Some(relative_b) = b.checked_sub(start) {
+            let a = relative_a % self.interval;
             let _b = relative_b % self.interval;
-            let (a, b) = (
-                relative_a % self.interval,
-                if _b == 0 { self.interval } else { _b },
-            );
-            // b > a from here
-
-            let l = b.checked_sub(a)?;
-            Some(a < self.duration || l >= self.interval)
+            let b = if _b == 0 { self.interval } else { _b };
+
+            let l = b.checked_sub(a).unwrap_or(0);
+            //   ╭a    ╭b
+            // ■■■■______■■■■______
+            // OR
+            //   ╭b  ╭a    ╭b'
+            // ■■■■______■■■■______
+            Some(b < a || a < self.duration || l >= self.interval)
         } else {
             Some(false)
         }