diff --git a/src/allocator/bump.rs b/src/allocator/bump.rs
index 355daef3..7d104eff 100644
--- a/src/allocator/bump.rs
+++ b/src/allocator/bump.rs
@@ -26,7 +26,7 @@ impl BumpAllocator {
     /// memory range is unused. Also, this method must be called only once.
     pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
         self.heap_start = heap_start;
-        self.heap_end = heap_start + heap_size;
+        self.heap_end = heap_start.saturating_add(heap_size);
         self.next = heap_start;
     }
 }
@@ -36,7 +36,7 @@ unsafe impl GlobalAlloc for Locked<BumpAllocator> {
         let mut bump = self.lock(); // get a mutable reference
 
         let alloc_start = align_up(bump.next, layout.align());
-        let alloc_end = alloc_start + layout.size();
+        let alloc_end = alloc_start.checked_add(layout.size()).expect("overflow");
 
         if alloc_end > bump.heap_end {
             ptr::null_mut() // out of memory
diff --git a/src/allocator/linked_list.rs b/src/allocator/linked_list.rs
index 699efbdf..3753511e 100644
--- a/src/allocator/linked_list.rs
+++ b/src/allocator/linked_list.rs
@@ -86,7 +86,7 @@ impl LinkedListAllocator {
     /// Returns the allocation start address on success.
     fn alloc_from_region(region: &ListNode, size: usize, align: usize) -> Result<usize, ()> {
         let alloc_start = align_up(region.start_addr(), align);
-        let alloc_end = alloc_start + size;
+        let alloc_end = alloc_start.checked_add(size).expect("overflow");
 
         if alloc_end > region.end_addr() {
             // region too small
@@ -125,7 +125,7 @@ unsafe impl GlobalAlloc for Locked<LinkedListAllocator> {
         let mut allocator = self.inner.lock();
 
         if let Some((region, alloc_start)) = allocator.find_region(size, align) {
-            let alloc_end = alloc_start + size;
+            let alloc_end = alloc_start.checked_add(size).expect("overflow");
             let excess_size = region.end_addr() - alloc_end;
             if excess_size > 0 {
                 allocator.add_free_region(alloc_end, excess_size);