diff --git a/kernel/src/memory/Heap.cpp b/kernel/src/memory/Heap.cpp
index fa663dce..3a2f4b67 100644
--- a/kernel/src/memory/Heap.cpp
+++ b/kernel/src/memory/Heap.cpp
@@ -125,8 +125,14 @@ static Option<HeapBlock*> split(HeapBlock* block, usize size)
 
 static Result<void> combine_forward(HeapBlock* block)
 {
+    // This block ends a memory range, cannot be combined with blocks outside its range.
+    if (block->status & BLOCK_END_MEM) return {};
+
     // The caller needs to ensure there is a next block.
     HeapBlock* const next = heap.next(block).value();
+    // This block starts a memory range, cannot be combined with blocks outside its range.
+    if (next->status & BLOCK_START_MEM) return {};
+
     heap.remove(next);
     next->magic = BLOCK_DEAD;
 
@@ -148,8 +154,13 @@ static Result<void> combine_forward(HeapBlock* block)
 
 static Result<HeapBlock*> combine_backward(HeapBlock* block)
 {
+    // This block starts a memory range, cannot be combined with blocks outside its range.
+    if (block->status & BLOCK_START_MEM) return block;
+
     // The caller needs to ensure there is a last block.
     HeapBlock* const last = heap.previous(block).value();
+    // This block ends a memory range, cannot be combined with blocks outside its range.
+    if (last->status & BLOCK_END_MEM) return block;
     heap.remove(block);
     block->magic = BLOCK_DEAD;