diff --git a/lib/std/core/allocators/heap_allocator.c3 b/lib/std/core/allocators/heap_allocator.c3
new file mode 100644
index 000000000..d55493b8a
--- /dev/null
+++ b/lib/std/core/allocators/heap_allocator.c3
@@ -0,0 +1,219 @@
+module std::core::mem::allocator;
+
+define MemoryAllocFn = fn char[]!(usz);
+
+struct SimpleHeapAllocator
+{
+	inline Allocator allocator;
+	MemoryAllocFn alloc_fn;
+	Header* free_list;
+}
+
+/**
+ * @require this "Unexpectedly missing the allocator"
+ * @require allocator "An underlying memory provider must be given"
+ * @require !this.free_list "The allocator may not be already initialized"
+ **/
+fn void SimpleHeapAllocator.init(SimpleHeapAllocator* this, MemoryAllocFn allocator)
+{
+	this.alloc_fn = allocator;
+	this.allocator = { &simple_heap_allocator_function };
+	this.free_list = null;
+}
+
+/**
+ * @require !alignment || math::is_power_of_2(alignment)
+ * @require this `unexpectedly missing the allocator`
+ */
+private fn void*! simple_heap_allocator_function(Allocator* this, usz size, usz alignment, usz offset, void* old_pointer, AllocationKind kind)
+{
+	SimpleHeapAllocator* heap = (SimpleHeapAllocator*)this;
+	switch (kind)
+    {
+        case ALIGNED_ALLOC:
+            return @aligned_alloc(heap._alloc, size, alignment, offset);
+		case ALLOC:
+            return heap._alloc(size);
+        case ALIGNED_CALLOC:
+            return @aligned_calloc(heap._calloc, size, alignment, offset);
+    	case CALLOC:
+            return heap._calloc(size);
+        case ALIGNED_REALLOC:
+            if (!size) nextcase ALIGNED_FREE;
+            if (!old_pointer) nextcase ALIGNED_CALLOC;
+            return @aligned_realloc(heap._calloc, heap._free, old_pointer, size, alignment, offset);
+        case REALLOC:
+            if (!size) nextcase FREE;
+            if (!old_pointer) nextcase CALLOC;
+            return heap._realloc(old_pointer, size);
+        case RESET:
+            return AllocationFailure.UNSUPPORTED_OPERATION!;
+        case ALIGNED_FREE:
+            @aligned_free(heap._free, old_pointer)?;
+            return null;
+        case FREE:
+            heap._free(old_pointer);
+            return null;
+        default:
+            unreachable();
+	}
+}
+
+/**
+ * @require this && old_pointer && bytes > 0
+ **/
+fn void*! SimpleHeapAllocator._realloc(SimpleHeapAllocator* this, void* old_pointer, usz bytes)
+{
+	// Find the block header.
+	Header* block = (Header*)old_pointer - 1;
+	if (block.size >= bytes) return old_pointer;
+	void* new = this._alloc(bytes)?;
+	usz max_to_copy = math::min(block.size, bytes);
+	mem::copy(new, old_pointer, max_to_copy);
+	this._free(old_pointer);
+	return new;
+}
+
+private fn void*! SimpleHeapAllocator._calloc(SimpleHeapAllocator* this, usz bytes)
+{
+	void* data = this._alloc(bytes)?;
+	mem::clear(data, bytes, DEFAULT_MEM_ALIGNMENT);
+	return data;
+}
+
+private fn void*! SimpleHeapAllocator._alloc(SimpleHeapAllocator* this, usz bytes)
+{
+	usz aligned_bytes = mem::aligned_offset(bytes, DEFAULT_MEM_ALIGNMENT);
+    if (!this.free_list)
+    {
+		this.add_block(aligned_bytes)?;
+    }
+
+	Header* current = this.free_list;
+	Header* previous = current;
+	while (current)
+	{
+		switch
+		{
+			case current.size >= aligned_bytes && current.size <= aligned_bytes + Header.sizeof + 64:
+				if (current == previous)
+				{
+					this.free_list = current.next;
+				}
+				else
+				{
+					previous.next = current.next;
+                }
+                current.next = null;
+                return current + 1;
+            case current.size > aligned_bytes:
+				Header* unallocated = (Header*)((char*)current + aligned_bytes + Header.sizeof);
+				unallocated.size = current.size - aligned_bytes;
+				unallocated.next = current.next;
+				if (current == this.free_list)
+				{
+					this.free_list = unallocated;
+				}
+				else
+				{
+					previous.next = unallocated;
+				}
+				current.size = aligned_bytes;
+				current.next = null;
+				return current + 1;
+			default:
+				previous = current;
+				current = current.next;
+		}
+	}
+	this.add_block(aligned_bytes)?;
+	return this.alloc(aligned_bytes);
+}
+
+private fn void! SimpleHeapAllocator.add_block(SimpleHeapAllocator* this, usz aligned_bytes)
+{
+	assert(mem::aligned_offset(aligned_bytes, DEFAULT_MEM_ALIGNMENT) == aligned_bytes);
+	char[] result = this.alloc_fn(aligned_bytes + Header.sizeof)?;
+	Header* new_block = (Header*)result.ptr;
+	new_block.size = result.len - Header.sizeof;
+	new_block.next = null;
+	this._free(new_block + 1);
+}
+
+
+private fn void SimpleHeapAllocator._free(SimpleHeapAllocator* this, void* ptr)
+{
+	// Empty ptr -> do nothing.
+	if (!ptr) return;
+
+	// Find the block header.
+	Header* block = (Header*)ptr - 1;
+
+	// No free list? Then just return this.
+	if (!this.free_list)
+	{
+		this.free_list = block;
+		return;
+	}
+
+	// Find where in the list it should be inserted.
+	Header* current = this.free_list;
+	Header* prev = current;
+	while (current)
+	{
+		if (block < current)
+		{
+			// Between prev and current
+			if (block > prev) break;
+			// Before current
+			if (current == prev) break;
+		}
+		prev = current;
+		current = prev.next;
+	}
+	if (current)
+	{
+		// Insert after the current block.
+        // Are the blocks adjacent?
+        if (current == (Header*)((char*)(block + 1) + block.size))
+        {
+            // Merge
+    		block.size += current.size + Header.sizeof;
+            block.next = current.next;
+        }
+        else
+        {
+            // Chain to current
+            block.next = current;
+        }
+	}
+	if (prev == current)
+	{
+		// Swap new start of free list
+		this.free_list = block;
+	}
+	else
+	{
+		// Prev adjacent?
+		if (block == (Header*)((char*)(prev + 1) + prev.size))
+		{
+    		prev.size += block.size + Header.sizeof;
+			prev.next = block.next;
+		}
+		else
+		{
+	        // Link prev to block
+	        prev.next = block;
+		}
+	}
+}
+
+private union Header
+{
+	struct
+	{
+		Header* next;
+  	    usz size;
+    }
+    usz align;
+}
diff --git a/lib/std/core/allocators/mem_allocator_fn.c3 b/lib/std/core/allocators/mem_allocator_fn.c3
index 52df46551..90fde2bb4 100644
--- a/lib/std/core/allocators/mem_allocator_fn.c3
+++ b/lib/std/core/allocators/mem_allocator_fn.c3
@@ -20,21 +20,24 @@ private fn void*! null_allocator_fn(Allocator* this, usz bytes, usz alignment, u
 	}
 }
 
-private struct AlignedBlock
+struct AlignedBlock
 {
 	usz len;
 	void* start;
 }
 
-
 /**
  * @require bytes > 0
  * @require alignment > 0
  **/
-private fn void* _libc_aligned_alloc(usz bytes, usz alignment, usz offset) @inline
+macro void*! @aligned_alloc(#alloc_fn, usz bytes, usz alignment, usz offset)
 {
 	usz header = mem::aligned_offset(AlignedBlock.sizeof + offset, alignment) - offset;
-	void* data = libc::malloc(header + bytes);
+	$if ($checks(#alloc_fn(bytes)?)):
+		void* data = #alloc_fn(header + bytes)?;
+	$else:
+		void* data = #alloc_fn(header + bytes);
+	$endif;
     void* mem = mem::aligned_pointer(data + header + offset, alignment) - offset;
 	assert(mem > data);
 	AlignedBlock* desc = (AlignedBlock*)mem - 1;
@@ -46,10 +49,14 @@ private fn void* _libc_aligned_alloc(usz bytes, usz alignment, usz offset) @inli
  * @require bytes > 0
  * @require alignment > 0
  **/
-private fn void* _libc_aligned_calloc(usz bytes, usz alignment, usz offset) @inline
+macro void*! @aligned_calloc(#calloc_fn, usz bytes, usz alignment, usz offset)
 {
 	usz header = mem::aligned_offset(AlignedBlock.sizeof + offset, alignment) - offset;
-	void* data = libc::calloc(header + bytes, 1);
+	$if ($checks(#calloc_fn(bytes)?)):
+		void* data = #calloc_fn(header + bytes)?;
+	$else:
+		void* data = #calloc_fn(header + bytes);
+	$endif;
 	void* mem = mem::aligned_pointer(data + header + offset, alignment) - offset;
 	AlignedBlock* desc = (AlignedBlock*)mem - 1;
 	assert(mem > data);
@@ -61,20 +68,28 @@ private fn void* _libc_aligned_calloc(usz bytes, usz alignment, usz offset) @inl
  * @require bytes > 0
  * @require alignment > 0
  **/
-private fn void* _libc_aligned_realloc(void* old_pointer, usz bytes, usz alignment, usz offset) @inline
+macro void*! @aligned_realloc(#calloc_fn, #free_fn, void* old_pointer, usz bytes, usz alignment, usz offset)
 {
 	AlignedBlock* desc = (AlignedBlock*)old_pointer - 1;
 	void* data_start = desc.start;
-    void* new_data = _libc_aligned_calloc(bytes, alignment, offset);
+    void* new_data = @aligned_calloc(#calloc_fn, bytes, alignment, offset)?;
 	mem::copy(new_data, old_pointer, desc.len > bytes ? desc.len : bytes, DEFAULT_MEM_ALIGNMENT, DEFAULT_MEM_ALIGNMENT);
-	libc::free(data_start);
+	$if ($checks(#free_fn(data_start)?)):
+	#free_fn(data_start)?;
+	$else:
+	#free_fn(data_start);
+	$endif;
 	return new_data;
 }
 
-private fn void _libc_aligned_free(void* old_pointer) @inline
+macro void! @aligned_free(#free_fn, void* old_pointer)
 {
 	AlignedBlock* desc = (AlignedBlock*)old_pointer - 1;
-	libc::free(desc.start);
+	$if ($checks(#free_fn(desc.start)?)):
+	#free_fn(desc.start)?;
+	$else:
+	#free_fn(desc.start);
+	$endif;
 }
 
 fn void*! libc_allocator_fn(Allocator* unused, usz bytes, usz alignment, usz offset, void* old_pointer, AllocationKind kind) @inline
@@ -86,17 +101,17 @@ fn void*! libc_allocator_fn(Allocator* unused, usz bytes, usz alignment, usz off
     switch (kind)
     {
         case ALIGNED_ALLOC:
-            data = _libc_aligned_alloc(bytes, alignment, offset);
+            data = @aligned_alloc(libc::malloc, bytes, alignment, offset)!!;
         case ALLOC:
             data = libc::malloc(bytes);
         case ALIGNED_CALLOC:
-            data = _libc_aligned_calloc(bytes, alignment, offset);
+            data = @aligned_calloc(fn void*(usz bytes) => libc::calloc(bytes, 1), bytes, alignment, offset)!!;
 		case CALLOC:
             data = libc::calloc(bytes, 1);
         case ALIGNED_REALLOC:
             if (!bytes) nextcase ALIGNED_FREE;
             if (!old_pointer) nextcase ALIGNED_CALLOC;
-			data = _libc_aligned_realloc(old_pointer, bytes, alignment, offset);
+            data = @aligned_realloc(fn void*(usz bytes) => libc::calloc(bytes, 1), libc::free, old_pointer, bytes, alignment, offset)!!;
         case REALLOC:
             if (!bytes) nextcase FREE;
             if (!old_pointer) nextcase CALLOC;
@@ -104,7 +119,7 @@ fn void*! libc_allocator_fn(Allocator* unused, usz bytes, usz alignment, usz off
         case RESET:
             return AllocationFailure.UNSUPPORTED_OPERATION!;
         case ALIGNED_FREE:
-            _libc_aligned_free(old_pointer);
+            @aligned_free(libc::free, old_pointer)!!;
             return null;
         case FREE:
             libc::free(old_pointer);
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index 85faef26f..63a28ced7 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -897,7 +897,7 @@ static inline bool sema_expr_analyse_hash_identifier(SemaContext *context, Expr
 	if (!sema_analyse_expr_lvalue_fold_const(decl->var.hash_var.context, expr))
 	{
 		// Poison the decl so we don't evaluate twice.
-		decl_poison(decl);
+		if (!global_context.suppress_errors) decl_poison(decl);
 		return false;
 	}
 	return true;
@@ -6534,6 +6534,12 @@ static inline Decl *sema_find_cached_lambda(SemaContext *context, Type *func_typ
 static inline bool sema_expr_analyse_lambda(SemaContext *context, Type *func_type, Expr *expr)
 {
 	Decl *decl = expr->lambda_expr;
+	if (!decl_ok(decl)) return false;
+	if (decl->resolve_status == RESOLVE_DONE)
+	{
+		expr->type = expr->type = type_get_ptr(decl->type);
+		return true;
+	}
 	bool in_macro = context->current_macro;
 	if (in_macro && decl->resolve_status != RESOLVE_DONE)
 	{
@@ -6616,6 +6622,7 @@ static inline bool sema_expr_analyse_lambda(SemaContext *context, Type *func_typ
 	vec_add(unit->module->lambdas_to_evaluate, decl);
 	expr->type = type_get_ptr(lambda_type);
 	if (in_macro) vec_add(original->func_decl.generated_lambda, decl);
+	decl->resolve_status = RESOLVE_DONE;
 	return true;
 FAIL_NO_INFER:
 	SEMA_ERROR(decl, "Inferred lambda expressions cannot be used unless the type can be determined.");
diff --git a/src/version.h b/src/version.h
index b3244c6af..de7ed85b5 100644
--- a/src/version.h
+++ b/src/version.h
@@ -1 +1 @@
-#define COMPILER_VERSION "0.4.25"
\ No newline at end of file
+#define COMPILER_VERSION "0.4.26"
\ No newline at end of file