diff --git a/CMakeLists.txt b/CMakeLists.txt
index e80e5f9..f274f86 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.28)
 project(HAL64 C)
 
 set(CMAKE_C_STANDARD 90)
-add_compile_options(-Ofast)
+add_compile_options(-O0)
 set(LEXER_DIR "${CMAKE_CURRENT_BINARY_DIR}")
 set(LEXER_OUT "${LEXER_DIR}/lexer.c")
 
diff --git a/src/hal64.c b/src/hal64.c
index f83bf9e..bbb6213 100644
--- a/src/hal64.c
+++ b/src/hal64.c
@@ -4,12 +4,26 @@
 #include "hal64.h"
 #include "utils/memory.h"
 
+static void
+free_instructions(Instruction *instructions, size_t count)
+{
+	size_t i;
+	for (i = 0; i < count; i++) {
+		if (instructions[i].op == OP_PUSH_LITERAL_STRING)
+			free(instructions[i].data.string.ptr);
+	}
+}
+
 void
 free_program(Program program)
 {
 	size_t i;
-	for (i = 0; i < program.functions_count; i++)
+	for (i = 0; i < program.functions_count; i++) {
+		free_instructions(
+			program.functions[i].instructions,
+			program.functions[i].instructions_count);
 		free(program.functions[i].instructions);
+	}
 	free(program.functions);
 }
 
diff --git a/src/vm.c b/src/vm.c
index 542fbfa..f7a0dc6 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -16,6 +16,7 @@ init_vm(void)
 	vm.operands_stack.capacity = 1024;
 	vm.pointers_stack.capacity = 1024;
 	vm.objects.capacity = 1024;
+	vm.allocated_heap_size = 0;
 	vm.call_stack.data = safe_malloc(vm.call_stack.capacity * sizeof(uint64_t));
 	vm.operands_stack.data = safe_malloc(vm.operands_stack.capacity * sizeof(uint64_t));
 	vm.pointers_stack.data = safe_malloc(vm.pointers_stack.capacity * sizeof(HeapObject *));
@@ -26,8 +27,15 @@ init_vm(void)
 void
 free_vm(VM vm)
 {
+	size_t i;
 	free(vm.call_stack.data);
 	free(vm.operands_stack.data);
+	free(vm.pointers_stack.data);
+	for (i = 0; i < vm.objects.size; i++) {
+		free(vm.objects.data[i]->data);
+		free(vm.objects.data[i]);
+	}
+	free(vm.objects.data);
 }
 
 static void
@@ -45,6 +53,7 @@ gc_sweep(VM *vm)
 	size_t i;
 	for (i = 0; i < vm->objects.size; i++) {
 		if (!vm->objects.data[i]->marked) {
+			vm->allocated_heap_size -= vm->objects.data[i]->size;
 			free(vm->objects.data[i]->data);
 			free(vm->objects.data[i]);
 			vm->objects.data[i] = vm->objects.data[vm->objects.size - 1];