diff --git a/09/instruction.cpp b/09/instruction.cpp
index 79c8a2f..c2b050a 100644
--- a/09/instruction.cpp
+++ b/09/instruction.cpp
@@ -15,7 +15,7 @@ void instruction_pushint::print(int indent, std::ostream& to) const {
 }
 
 void instruction_pushint::gen_llvm(llvm_context& ctx, Function* f) const {
-    ctx.create_push(f, ctx.create_num(ctx.create_i32(value)));
+    ctx.create_push(f, ctx.create_num(f, ctx.create_i32(value)));
 }
 
 void instruction_pushglobal::print(int indent, std::ostream& to) const {
@@ -26,7 +26,7 @@ void instruction_pushglobal::print(int indent, std::ostream& to) const {
 void instruction_pushglobal::gen_llvm(llvm_context& ctx, Function* f) const {
     auto& global_f = ctx.custom_functions.at("f_" + name);
     auto arity = ctx.create_i32(global_f->arity);
-    ctx.create_push(f, ctx.create_global(global_f->function, arity));
+    ctx.create_push(f, ctx.create_global(f, global_f->function, arity));
 }
 
 void instruction_push::print(int indent, std::ostream& to) const {
@@ -55,7 +55,7 @@ void instruction_mkapp::print(int indent, std::ostream& to) const {
 void instruction_mkapp::gen_llvm(llvm_context& ctx, Function* f) const {
     auto left = ctx.create_pop(f);
     auto right = ctx.create_pop(f);
-    ctx.create_push(f, ctx.create_app(left, right));
+    ctx.create_push(f, ctx.create_app(f, left, right));
 }
 
 void instruction_update::print(int indent, std::ostream& to) const {
@@ -146,7 +146,7 @@ void instruction_binop::gen_llvm(llvm_context& ctx, Function* f) const {
         case TIMES: result = ctx.builder.CreateMul(left_int, right_int); break;
         case DIVIDE: result = ctx.builder.CreateSDiv(left_int, right_int); break;
     }
-    ctx.create_push(f, ctx.create_num(result));
+    ctx.create_push(f, ctx.create_num(f, result));
 }
 
 void instruction_eval::print(int indent, std::ostream& to) const {
diff --git a/09/llvm_context.cpp b/09/llvm_context.cpp
index 18ce6e4..99ab480 100644
--- a/09/llvm_context.cpp
+++ b/09/llvm_context.cpp
@@ -5,7 +5,9 @@ using namespace llvm;
 
 void llvm_context::create_types() {
     stack_type = StructType::create(ctx, "stack");
+    gmachine_type = StructType::create(ctx, "gmachine");
     stack_ptr_type = PointerType::getUnqual(stack_type);
+    gmachine_ptr_type = PointerType::getUnqual(gmachine_type);
     tag_type = IntegerType::getInt8Ty(ctx);
     struct_types["node_base"] = StructType::create(ctx, "node_base");
     struct_types["node_app"] = StructType::create(ctx, "node_app");
@@ -14,10 +16,16 @@ void llvm_context::create_types() {
     struct_types["node_ind"] = StructType::create(ctx, "node_ind");
     struct_types["node_data"] = StructType::create(ctx, "node_data");
     node_ptr_type = PointerType::getUnqual(struct_types.at("node_base"));
-    function_type = FunctionType::get(Type::getVoidTy(ctx), { stack_ptr_type }, false);
+    function_type = FunctionType::get(Type::getVoidTy(ctx), { gmachine_ptr_type }, false);
 
+    gmachine_type->setBody(
+            stack_ptr_type,
+            node_ptr_type
+    );
     struct_types.at("node_base")->setBody(
-            IntegerType::getInt32Ty(ctx)
+            IntegerType::getInt32Ty(ctx),
+            IntegerType::getInt8Ty(ctx),
+            node_ptr_type
     );
     struct_types.at("node_app")->setBody(
             struct_types.at("node_base"),
@@ -82,34 +90,40 @@ void llvm_context::create_functions() {
             "stack_popn",
             &module
     );
-    functions["stack_slide"] = Function::Create(
-            FunctionType::get(void_type, { stack_ptr_type, sizet_type }, false),
+    functions["gmachine_slide"] = Function::Create(
+            FunctionType::get(void_type, { gmachine_ptr_type, sizet_type }, false),
             Function::LinkageTypes::ExternalLinkage,
-            "stack_slide",
+            "gmachine_slide",
             &module
     );
-    functions["stack_update"] = Function::Create(
-            FunctionType::get(void_type, { stack_ptr_type, sizet_type }, false),
+    functions["gmachine_update"] = Function::Create(
+            FunctionType::get(void_type, { gmachine_ptr_type, sizet_type }, false),
             Function::LinkageTypes::ExternalLinkage,
-            "stack_update",
+            "gmachine_update",
             &module
     );
-    functions["stack_alloc"] = Function::Create(
-            FunctionType::get(void_type, { stack_ptr_type, sizet_type }, false),
+    functions["gmachine_alloc"] = Function::Create(
+            FunctionType::get(void_type, { gmachine_ptr_type, sizet_type }, false),
             Function::LinkageTypes::ExternalLinkage,
-            "stack_alloc",
+            "gmachine_alloc",
             &module
     );
-    functions["stack_pack"] = Function::Create(
-            FunctionType::get(void_type, { stack_ptr_type, sizet_type, tag_type }, false),
+    functions["gmachine_pack"] = Function::Create(
+            FunctionType::get(void_type, { gmachine_ptr_type, sizet_type, tag_type }, false),
             Function::LinkageTypes::ExternalLinkage,
-            "stack_pack",
+            "gmachine_pack",
             &module
     );
-    functions["stack_split"] = Function::Create(
-            FunctionType::get(node_ptr_type, { stack_ptr_type, sizet_type }, false),
+    functions["gmachine_split"] = Function::Create(
+            FunctionType::get(void_type, { gmachine_ptr_type, sizet_type }, false),
             Function::LinkageTypes::ExternalLinkage,
-            "stack_split",
+            "gmachine_split",
+            &module
+    );
+    functions["gmachine_track"] = Function::Create(
+            FunctionType::get(node_ptr_type, { gmachine_ptr_type, node_ptr_type }, false),
+            Function::LinkageTypes::ExternalLinkage,
+            "gmachine_track",
             &module
     );
 
@@ -139,14 +153,8 @@ void llvm_context::create_functions() {
             &module
     );
 
-    functions["eval"] = Function::Create(
-            FunctionType::get(node_ptr_type, { node_ptr_type }, false),
-            Function::LinkageTypes::ExternalLinkage,
-            "eval",
-            &module
-    );
     functions["unwind"] = Function::Create(
-            FunctionType::get(void_type, { stack_ptr_type }, false),
+            FunctionType::get(void_type, { gmachine_ptr_type }, false),
             Function::LinkageTypes::ExternalLinkage,
             "unwind",
             &module
@@ -165,40 +173,44 @@ ConstantInt* llvm_context::create_size(size_t i) {
 
 Value* llvm_context::create_pop(Function* f) {
     auto pop_f = functions.at("stack_pop");
-    return builder.CreateCall(pop_f, { f->arg_begin() });
+    return builder.CreateCall(pop_f, { unwrap_gmachine_stack_ptr(f->arg_begin()) });
 }
 Value* llvm_context::create_peek(Function* f, Value* off) {
     auto peek_f = functions.at("stack_peek");
-    return builder.CreateCall(peek_f, { f->arg_begin(), off });
+    return builder.CreateCall(peek_f, { unwrap_gmachine_stack_ptr(f->arg_begin()), off });
 }
 void llvm_context::create_push(Function* f, Value* v) {
     auto push_f = functions.at("stack_push");
-    builder.CreateCall(push_f, { f->arg_begin(), v });
+    builder.CreateCall(push_f, { unwrap_gmachine_stack_ptr(f->arg_begin()), v });
 }
 void llvm_context::create_popn(Function* f, Value* off) {
     auto popn_f = functions.at("stack_popn");
-    builder.CreateCall(popn_f, { f->arg_begin(), off });
+    builder.CreateCall(popn_f, { unwrap_gmachine_stack_ptr(f->arg_begin()), off });
 }
 void llvm_context::create_update(Function* f, Value* off) {
-    auto update_f = functions.at("stack_update");
+    auto update_f = functions.at("gmachine_update");
     builder.CreateCall(update_f, { f->arg_begin(), off });
 }
 void llvm_context::create_pack(Function* f, Value* c, Value* t) {
-    auto pack_f = functions.at("stack_pack");
+    auto pack_f = functions.at("gmachine_pack");
     builder.CreateCall(pack_f, { f->arg_begin(), c, t });
 }
 void llvm_context::create_split(Function* f, Value* c) {
-    auto split_f = functions.at("stack_split");
+    auto split_f = functions.at("gmachine_split");
     builder.CreateCall(split_f, { f->arg_begin(), c });
 }
 void llvm_context::create_slide(Function* f, Value* off) {
-    auto slide_f = functions.at("stack_slide");
+    auto slide_f = functions.at("gmachine_slide");
     builder.CreateCall(slide_f, { f->arg_begin(), off });
 }
 void llvm_context::create_alloc(Function* f, Value* n) {
-    auto alloc_f = functions.at("stack_alloc");
+    auto alloc_f = functions.at("gmachine_alloc");
     builder.CreateCall(alloc_f, { f->arg_begin(), n });
 }
+Value* llvm_context::create_track(Function* f, Value* v) {
+    auto track_f = functions.at("gmachine_track");
+    return builder.CreateCall(track_f, { f->arg_begin(), v });
+}
 
 Value* llvm_context::create_eval(Value* e) {
     auto eval_f = functions.at("eval");
@@ -210,6 +222,11 @@ void llvm_context::create_unwind(Function* f) {
     builder.CreateCall(unwind_f, { f->args().begin() });
 }
 
+Value* llvm_context::unwrap_gmachine_stack_ptr(Value* g) {
+    auto offset_0 = create_i32(0);
+    return builder.CreateGEP(g, { offset_0, offset_0 });
+}
+
 Value* llvm_context::unwrap_num(Value* v) {
     auto num_ptr_type = PointerType::getUnqual(struct_types.at("node_num"));
     auto cast = builder.CreatePointerCast(v, num_ptr_type);
@@ -218,9 +235,10 @@ Value* llvm_context::unwrap_num(Value* v) {
     auto int_ptr = builder.CreateGEP(cast, { offset_0, offset_1 });
     return builder.CreateLoad(int_ptr);
 }
-Value* llvm_context::create_num(Value* v) {
+Value* llvm_context::create_num(Function* f, Value* v) {
     auto alloc_num_f = functions.at("alloc_num");
-    return builder.CreateCall(alloc_num_f, { v });
+    auto alloc_num_call = builder.CreateCall(alloc_num_f, { v });
+    return create_track(f, alloc_num_call);
 }
 
 Value* llvm_context::unwrap_data_tag(Value* v) {
@@ -232,20 +250,20 @@ Value* llvm_context::unwrap_data_tag(Value* v) {
     return builder.CreateLoad(tag_ptr);
 }
 
-Value* llvm_context::create_global(Value* f, Value* a) {
+Value* llvm_context::create_global(Function* f, Value* gf, Value* a) {
     auto alloc_global_f = functions.at("alloc_global");
-    return builder.CreateCall(alloc_global_f, { f, a });
+    auto alloc_global_call = builder.CreateCall(alloc_global_f, { gf, a });
+    return create_track(f, alloc_global_call);
 }
 
-Value* llvm_context::create_app(Value* l, Value* r) {
+Value* llvm_context::create_app(Function* f, Value* l, Value* r) {
     auto alloc_app_f = functions.at("alloc_app");
-    return builder.CreateCall(alloc_app_f, { l, r });
+    auto alloc_app_call = builder.CreateCall(alloc_app_f, { l, r });
+    return create_track(f, alloc_app_call);
 }
 
 llvm::Function* llvm_context::create_custom_function(std::string name, int32_t arity) {
     auto void_type = llvm::Type::getVoidTy(ctx);
-    auto function_type =
-        llvm::FunctionType::get(void_type, { stack_ptr_type }, false);
     auto new_function = llvm::Function::Create(
             function_type,
             llvm::Function::LinkageTypes::ExternalLinkage,
diff --git a/09/llvm_context.hpp b/09/llvm_context.hpp
index 7c9a6a6..89e145e 100644
--- a/09/llvm_context.hpp
+++ b/09/llvm_context.hpp
@@ -4,6 +4,7 @@
 #include <llvm/IR/LLVMContext.h>
 #include <llvm/IR/IRBuilder.h>
 #include <llvm/IR/Module.h>
+#include <llvm/IR/Value.h>
 #include <map>
 
 struct llvm_context {
@@ -23,7 +24,9 @@ struct llvm_context {
     std::map<std::string, llvm::StructType*> struct_types;
 
     llvm::StructType* stack_type;
+    llvm::StructType* gmachine_type;
     llvm::PointerType* stack_ptr_type;
+    llvm::PointerType* gmachine_ptr_type;
     llvm::PointerType* node_ptr_type;
     llvm::IntegerType* tag_type;
     llvm::FunctionType* function_type;
@@ -50,18 +53,21 @@ struct llvm_context {
     void create_split(llvm::Function*, llvm::Value*);
     void create_slide(llvm::Function*, llvm::Value*);
     void create_alloc(llvm::Function*, llvm::Value*);
+    llvm::Value* create_track(llvm::Function*, llvm::Value*);
 
     llvm::Value* create_eval(llvm::Value*);
     void create_unwind(llvm::Function*);
 
+    llvm::Value* unwrap_gmachine_stack_ptr(llvm::Value*);
+
     llvm::Value* unwrap_num(llvm::Value*);
-    llvm::Value* create_num(llvm::Value*);
+    llvm::Value* create_num(llvm::Function*, llvm::Value*);
 
     llvm::Value* unwrap_data_tag(llvm::Value*);
 
-    llvm::Value* create_global(llvm::Value*, llvm::Value*);
+    llvm::Value* create_global(llvm::Function*, llvm::Value*, llvm::Value*);
 
-    llvm::Value* create_app(llvm::Value*, llvm::Value*);
+    llvm::Value* create_app(llvm::Function*, llvm::Value*, llvm::Value*);
 
     llvm::Function* create_custom_function(std::string name, int32_t arity);
 };
diff --git a/09/runtime.c b/09/runtime.c
index ebae7ae..c5f855f 100644
--- a/09/runtime.c
+++ b/09/runtime.c
@@ -25,7 +25,7 @@ struct node_num* alloc_num(int32_t n) {
     return node;
 }
 
-struct node_global* alloc_global(void (*f)(struct stack*), int32_t a) {
+struct node_global* alloc_global(void (*f)(struct gmachine*), int32_t a) {
     struct node_global* node = (struct node_global*) alloc_node();
     node->base.tag = NODE_GLOBAL;
     node->arity = a;
@@ -40,6 +40,12 @@ struct node_ind* alloc_ind(struct node_base* n) {
     return node;
 }
 
+void free_node_direct(struct node_base* n) {
+    if(n->tag == NODE_DATA) {
+        free(((struct node_data*) n)->array);
+    }
+}
+
 void stack_init(struct stack* s) {
     s->size = 4;
     s->count = 0;
@@ -74,49 +80,81 @@ void stack_popn(struct stack* s, size_t n) {
     s->count -= n;
 }
 
-void stack_slide(struct stack* s, size_t n) {
-    assert(s->count > n);
-    s->data[s->count - n - 1] = s->data[s->count - 1];
-    s->count -= n;
+void gmachine_init(struct gmachine* g) {
+    stack_init(&g->stack);
+    g->nodes = NULL;
 }
 
-void stack_update(struct stack* s, size_t o) {
-    assert(s->count > o + 1);
-    struct node_ind* ind = (struct node_ind*) s->data[s->count - o - 2];
-    ind->base.tag = NODE_IND;
-    ind->next = s->data[s->count -= 1];
-}
+void gmachine_free(struct gmachine* g) {
+    stack_free(&g->stack);
+    struct node_base* to_free = g->nodes;
+    struct node_base* next;
 
-void stack_alloc(struct stack* s, size_t o) {
-    while(o--) {
-        stack_push(s, (struct node_base*) alloc_ind(NULL));
+    while(to_free) {
+        next = to_free->gc_next;
+        free_node_direct(to_free);
+        free(to_free);
+        to_free = next;
     }
 }
 
-void stack_pack(struct stack* s, size_t n, int8_t t) {
-    assert(s->count >= n);
+void gmachine_slide(struct gmachine* g, size_t n) {
+    assert(g->stack.count > n);
+    g->stack.data[g->stack.count - n - 1] = g->stack.data[g->stack.count - 1];
+    g->stack.count -= n;
+}
+
+void gmachine_update(struct gmachine* g, size_t o) {
+    assert(g->stack.count > o + 1);
+    struct node_ind* ind =
+        (struct node_ind*) g->stack.data[g->stack.count - o - 2];
+    ind->base.tag = NODE_IND;
+    ind->next = g->stack.data[g->stack.count -= 1];
+}
+
+void gmachine_alloc(struct gmachine* g, size_t o) {
+    while(o--) {
+        stack_push(&g->stack,
+                gmachine_track(g, (struct node_base*) alloc_ind(NULL)));
+    }
+}
+
+void gmachine_pack(struct gmachine* g, size_t n, int8_t t) {
+    assert(g->stack.count >= n);
 
     struct node_base** data = malloc(sizeof(*data) * n);
     assert(data != NULL);
-    memcpy(data, &s->data[s->count - n], n * sizeof(*data));
+    memcpy(data, &g->stack.data[g->stack.count - n], n * sizeof(*data));
 
     struct node_data* new_node = (struct node_data*) alloc_node();
     new_node->array = data;
     new_node->base.tag = NODE_DATA;
     new_node->tag = t;
 
-    stack_popn(s, n);
-    stack_push(s, (struct node_base*) new_node);
+    stack_popn(&g->stack, n);
+    stack_push(&g->stack, gmachine_track(g, (struct node_base*) new_node));
 }
 
-void stack_split(struct stack* s, size_t n) {
-    struct node_data* node = (struct node_data*) stack_pop(s);
+void gmachine_split(struct gmachine* g, size_t n) {
+    struct node_data* node = (struct node_data*) stack_pop(&g->stack);
     for(size_t i = 0; i < n; i++) {
-        stack_push(s, node->array[i]);
+        stack_push(&g->stack, node->array[i]);
     }
 }
 
-void unwind(struct stack* s) {
+struct node_base* gmachine_track(struct gmachine* g, struct node_base* b) {
+    b->gc_next = g->nodes;
+    g->nodes = b;
+    return b;
+}
+
+void gmachine_gc(struct gmachine* g) {
+
+}
+
+void unwind(struct gmachine* g) {
+    struct stack* s = &g->stack;
+
     while(1) {
         struct node_base* peek = stack_peek(s, 0);
         if(peek->tag == NODE_APP) {
@@ -131,7 +169,7 @@ void unwind(struct stack* s) {
                     = ((struct node_app*) s->data[s->count - i - 1])->right;
             }
 
-            n->function(s);
+            n->function(g);
         } else if(peek->tag == NODE_IND) {
             struct node_ind* n = (struct node_ind*) peek;
             stack_pop(s);
@@ -142,17 +180,7 @@ void unwind(struct stack* s) {
     }
 }
 
-struct node_base* eval(struct node_base* n) {
-    struct stack program_stack;
-    stack_init(&program_stack);
-    stack_push(&program_stack, n);
-    unwind(&program_stack);
-    struct node_base* result = stack_pop(&program_stack);
-    stack_free(&program_stack);
-    return result;
-}
-
-extern void f_main(struct stack* s);
+extern void f_main(struct gmachine* s);
 
 void print_node(struct node_base* n) {
     if(n->tag == NODE_APP) {
@@ -174,10 +202,17 @@ void print_node(struct node_base* n) {
 }
 
 int main(int argc, char** argv) {
+    struct gmachine gmachine;
     struct node_global* first_node = alloc_global(f_main, 0);
-    struct node_base* result = eval((struct node_base*) first_node);
+    struct node_base* result;
 
+    gmachine_init(&gmachine);
+    gmachine_track(&gmachine, (struct node_base*) first_node);
+    stack_push(&gmachine.stack, (struct node_base*) first_node);
+    unwind(&gmachine);
+    result = stack_pop(&gmachine.stack);
     printf("Result: ");
     print_node(result);
     putchar('\n');
+    gmachine_free(&gmachine);
 }
diff --git a/09/runtime.h b/09/runtime.h
index baaaaae..c1f9dee 100644
--- a/09/runtime.h
+++ b/09/runtime.h
@@ -1,7 +1,7 @@
 #pragma once
 #include <stdlib.h>
 
-struct stack;
+struct gmachine;
 
 enum node_tag {
     NODE_APP,
@@ -13,6 +13,8 @@ enum node_tag {
 
 struct node_base {
     enum node_tag tag;
+    int8_t gc_color;
+    struct node_base* gc_next;
 };
 
 struct node_app {
@@ -29,7 +31,7 @@ struct node_num {
 struct node_global {
     struct node_base base;
     int32_t arity;
-    void (*function)(struct stack*);
+    void (*function)(struct gmachine*);
 };
 
 struct node_ind {
@@ -46,8 +48,9 @@ struct node_data {
 struct node_base* alloc_node();
 struct node_app* alloc_app(struct node_base* l, struct node_base* r);
 struct node_num* alloc_num(int32_t n);
-struct node_global* alloc_global(void (*f)(struct stack*), int32_t a);
+struct node_global* alloc_global(void (*f)(struct gmachine*), int32_t a);
 struct node_ind* alloc_ind(struct node_base* n);
+void free_node_direct(struct node_base*);
 
 struct stack {
     size_t size;
@@ -61,10 +64,18 @@ void stack_push(struct stack* s, struct node_base* n);
 struct node_base* stack_pop(struct stack* s);
 struct node_base* stack_peek(struct stack* s, size_t o);
 void stack_popn(struct stack* s, size_t n);
-void stack_slide(struct stack* s, size_t n);
-void stack_update(struct stack* s, size_t o);
-void stack_alloc(struct stack* s, size_t o);
-void stack_pack(struct stack* s, size_t n, int8_t t);
-void stack_split(struct stack* s, size_t n);
 
-struct node_base* eval(struct node_base* n);
+struct gmachine {
+    struct stack stack;
+    struct node_base* nodes;
+};
+
+void gmachine_init(struct gmachine* g);
+void gmachine_free(struct gmachine* g);
+void gmachine_slide(struct gmachine* g, size_t n);
+void gmachine_update(struct gmachine* g, size_t o);
+void gmachine_alloc(struct gmachine* g, size_t o);
+void gmachine_pack(struct gmachine* g, size_t n, int8_t t);
+void gmachine_split(struct gmachine* g, size_t n);
+struct node_base* gmachine_track(struct gmachine* g, struct node_base* b);
+void gmachine_gc(struct gmachine* g);