diff --git a/src/ast.c b/src/ast.c
index 97bce46..32f78de 100644
--- a/src/ast.c
+++ b/src/ast.c
@@ -2,7 +2,7 @@
 
 #include "include/ast.h"
 #include "include/dstr.h"
-#include "include/htab.h"
+#include "include/scope.h"
 #include "include/util.h"
 
 extern AST* root;
@@ -28,7 +28,7 @@ AST* ast_init(ASTType type, void* data) {
     return ast;
 }
 
-AST* ast_init_scope(ASTType type, void* data, HTab* scope) {
+AST* ast_init_scope(ASTType type, void* data, Scope* scope) {
     AST* ast = malloc(sizeof(AST));
 
     ast->type = type;
@@ -53,8 +53,8 @@ void ast_destroy(AST* ast) {
             log_dbgf("Unknown ast type %d (max: %d)", ast->type, AST_TYPE_MAX);
     }
 
+    scope_destroy_psv(ast->scope);
     free(ast);
-    htab_destroy(ast->scope);
 }
 
 void ast_print(AST* ast) { ast_print_i(ast, 0); }
diff --git a/src/exec.c b/src/exec.c
index cf8a568..276c662 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -9,12 +9,11 @@
 #include "include/stack.h"
 #include "include/util.h"
 
-extern AST* root;
-
 AST* exec_find(char* name);
 
 AST* exec_start(AST* ast) {
     log_dbg("Started execution.");
+
     Stack* scope = stack_init();
 
     HTab* global = htab_init();
@@ -47,13 +46,13 @@ AST* exec_block(AST* ast) {
     ASTBlockData* block = (ASTBlockData*)ast->data;
 
     HTab* local = htab_init();
-    //stack_push(scope, local);
+    // stack_push(scope, local);
 
     // Loop through all but last ast.
     for (int i = 0; i < block->ln - 1; i++) exec_exp(block->inside[i]);
     AST* last = exec_exp(block->inside[block->ln - 1]);
 
-    //stack_pop(scope);
+    // stack_pop(scope);
     htab_destroy(local);
 
     return last;
@@ -88,7 +87,7 @@ AST* exec_cf(AST* ast, size_t argc, AST** argv) {
     for (int i = 0; i < argc; i++) {
         char* key = ((ASTArgData*)fdef->argv[i]->data)->name;
         AST* val = argv[i];
-        //htab_ins(scope->buf[scope->ln - 1], key, val);
+        // htab_ins(scope->buf[scope->ln - 1], key, val);
     }
 
     return exec_exp(fdef->body);
@@ -111,7 +110,7 @@ AST* exec_vdef(AST* ast) {
     ASTVDefData* data = (ASTVDefData*)ast->data;
     AST* val = data->val;
     char* key = data->name;
-    //htab_ins(scope->buf[scope->ln - 1], key, val);
+    // htab_ins(scope->buf[scope->ln - 1], key, val);
     return exec_exp(val);
 }
 
@@ -138,7 +137,7 @@ AST* exec_fdef(AST* ast) {
     ASTFDefData* fdef = (ASTFDefData*)ast->data;
     AST* val = fdef->body;
     char* key = fdef->name;
-    //htab_ins(scope->buf[scope->ln - 1], key, val);
+    // htab_ins(scope->buf[scope->ln - 1], key, val);
     return val; // Function definitions return function body.
 }
 
diff --git a/src/include/ast.h b/src/include/ast.h
index 00da251..e384673 100644
--- a/src/include/ast.h
+++ b/src/include/ast.h
@@ -2,6 +2,7 @@
 #define AST_H
 
 #include "htab.h"
+#include "scope.h"
 #include <stdlib.h>
 
 // The type of an `AST`.
@@ -32,13 +33,13 @@ typedef enum {
 typedef struct {
     ASTType type; // The type of the `AST`.
     void* data;   // The data of the `AST`.
-    HTab* scope;  // The scope of the `AST`.
+    Scope* scope; // The scope of the `AST`.
 } AST;
 
 // Create a new `AST`.
 AST* ast_init(ASTType type, void* data);
 // Create a new `AST` with a specified scope.
-AST* ast_init_scope(ASTType type, void* data, HTab* scope);
+AST* ast_init_scope(ASTType type, void* data, Scope* scope);
 // Destroy an `AST`, recursively.
 void ast_destroy(AST* ast);
 // Print an `AST`, recursively.
diff --git a/test/Unity b/test/Unity
index cdf1d02..73237c5 160000
--- a/test/Unity
+++ b/test/Unity
@@ -1 +1 @@
-Subproject commit cdf1d0297effc2736ee847e557b4275b4f02310b
+Subproject commit 73237c5d224169c7b4d2ec8321f9ac92e8071708