diff --git a/src/Makefile.am b/src/Makefile.am
index bd5d691..56c48b6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -18,8 +18,8 @@ bin_PROGRAMS = 42sh
 		parser/libparser.a \
 		lexer/liblexer.a \
 		io_backend/libio_backend.a \
-		expansion/libexpansion.a \
 		execution/libexecution.a \
+		expansion/libexpansion.a \
 		utils/libutils.a
 
 # ================ TESTS ================
diff --git a/src/execution/execution.c b/src/execution/execution.c
index ec0fe21..a98ff2f 100644
--- a/src/execution/execution.c
+++ b/src/execution/execution.c
@@ -9,7 +9,9 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+#include "../expansion/expansion.h"
 #include "../utils/ast/ast.h"
+#include "../utils/hash_map/hash_map.h"
 
 // --- Helpers ---
 
@@ -205,7 +207,7 @@ static int exec_command(struct ast_command *command)
  * @param ast The AST to execute
  * @return int The exit status of the last executed command.
  */
-int execution(struct ast *ast)
+int execution(struct ast *ast, struct hash_map *vars)
 {
     if (!ast)
     {
@@ -219,18 +221,20 @@ int execution(struct ast *ast)
     }
     case AST_CMD: {
         struct ast_command *command = ast_get_command(ast);
+        if (!expand(command, vars))
+            fprintf(stderr, "Error: Variable expansion failed\n");
         return exec_command(command);
     }
     case AST_IF: {
         struct ast_if *if_node = ast_get_if(ast);
-        int cond = execution(if_node->condition);
+        int cond = execution(if_node->condition, vars);
         if (cond == 0) // True
         {
-            return execution(if_node->then_clause);
+            return execution(if_node->then_clause, vars);
         }
         else // False
         {
-            return execution(if_node->else_clause);
+            return execution(if_node->else_clause, vars);
         }
     }
     case AST_LIST: {
@@ -240,25 +244,25 @@ int execution(struct ast *ast)
         while (cur)
         {
             struct ast *child = (struct ast *)cur->data;
-            ret = execution(child);
+            ret = execution(child, vars);
             cur = cur->next;
         }
         return ret;
     }
     case AST_AND_OR: {
         struct ast_and_or *ao_node = ast_get_and_or(ast);
-        int left_ret = execution(ao_node->left);
+        int left_ret = execution(ao_node->left, vars);
 
         if (ao_node->type == AST_AND_OR_TYPE_AND)
         {
             if (left_ret == 0)
-                return execution(ao_node->right);
+                return execution(ao_node->right, vars);
             return left_ret;
         }
         else // OR
         {
             if (left_ret != 0)
-                return execution(ao_node->right);
+                return execution(ao_node->right, vars);
             return left_ret;
         }
     }
@@ -335,7 +339,7 @@ int execution(struct ast *ast)
             close(new_fd);
         }
 
-        int ret = execution(redir->child);
+        int ret = execution(redir->child, vars);
 
         if (saved_fd != -1)
         {
diff --git a/src/execution/execution.h b/src/execution/execution.h
index aacacc3..872f0ad 100644
--- a/src/execution/execution.h
+++ b/src/execution/execution.h
@@ -3,6 +3,7 @@
 
 #include "../utils/ast/ast.h"
 #include "../utils/lists/lists.h"
+#include "../utils/hash_map/hash_map.h"
 
 /**
  * @brief Execute the AST
@@ -10,6 +11,6 @@
  * @param ast Pointer to the AST structure
  * @return int Execution status code of the last command
  */
-int execution(struct ast *ast);
+int execution(struct ast *ast, struct hash_map *vars);
 
 #endif /* ! EXECUTION_H */
diff --git a/src/expansion/expansion.c b/src/expansion/expansion.c
index 407e2f7..ab6241e 100644
--- a/src/expansion/expansion.c
+++ b/src/expansion/expansion.c
@@ -115,11 +115,10 @@ static bool expand_var(char **str, size_t pos, const struct hash_map *vars)
     return false;
 }
 
-struct ast_command *expand(struct ast_command *command,
-                           const struct hash_map *vars)
+bool expand(struct ast_command *command, const struct hash_map *vars)
 {
     if (command == NULL)
-        return NULL;
+        return false;
 
     char *str;
     size_t len;
@@ -150,7 +149,7 @@ struct ast_command *expand(struct ast_command *command,
                 // variable expansion
                 bool r = expand_var(&str, i, vars);
                 if (r == false || str == NULL)
-                    return NULL;
+                    return false;
 
                 i--; // -1 because loop will increment i
             }
@@ -160,7 +159,7 @@ struct ast_command *expand(struct ast_command *command,
         {
             // error: quote not closed
             fprintf(stderr, "Error: quote not closed in string: %s\n", str);
-            return NULL;
+            return false;
         }
 
         if (len != strlen(str))
@@ -169,12 +168,12 @@ struct ast_command *expand(struct ast_command *command,
             if (new_str == NULL)
             {
                 // error: realloc fail
-                return NULL;
+                return false;
             }
             l->data = new_str;
         }
 
         l = l->next;
     }
-    return command;
+    return true;
 }
diff --git a/src/expansion/expansion.h b/src/expansion/expansion.h
index 7211ae3..64b016f 100644
--- a/src/expansion/expansion.h
+++ b/src/expansion/expansion.h
@@ -1,6 +1,7 @@
 #ifndef EXPANSION_H
 #define EXPANSION_H
 
+#include <stdbool.h>
 #include <stddef.h>
 
 #include "../utils/hash_map/hash_map.h"
@@ -20,7 +21,6 @@ size_t parse_var_name(char *str, char **res);
  * @param vars The hash map containing variables.
  * @return A new AST command with variables expanded, or NULL on error.
  */
-struct ast_command *expand(struct ast_command *command,
-                           const struct hash_map *vars);
+bool expand(struct ast_command *command, const struct hash_map *vars);
 
 #endif /* ! EXPANSION_H */
diff --git a/src/main.c b/src/main.c
index b86a9a7..10644ac 100644
--- a/src/main.c
+++ b/src/main.c
@@ -85,7 +85,9 @@ int main(int argc, char **argv)
     while (command_ast != NULL && command_ast->type != AST_END)
     {
         // Execute AST
-        return_code = execution(command_ast);
+        return_code = execution(command_ast, vars);
+
+        // set $? variable
 
         ast_free(&command_ast);
 
diff --git a/src/utils/vars/vars.c b/src/utils/vars/vars.c
index 8d762da..290566d 100644
--- a/src/utils/vars/vars.c
+++ b/src/utils/vars/vars.c
@@ -12,12 +12,7 @@
 
 #define VARS_INITIAL_SIZE 16
 
-struct hash_map *vars_init(void)
-{
-    return hash_map_init(VARS_INITIAL_SIZE);
-}
-
-void vars_default(struct hash_map *vars)
+static void vars_default(struct hash_map *vars)
 {
     set_var_copy(vars, "?", "0");
     pid_t pid = getpid();
@@ -26,6 +21,14 @@ void vars_default(struct hash_map *vars)
     set_var_copy(vars, "$", pid_str);
 }
 
+struct hash_map *vars_init(void)
+{
+    struct hash_map *vars = hash_map_init(VARS_INITIAL_SIZE);
+    if (vars != NULL)
+        vars_default(vars);
+    return vars;
+}
+
 short short_random(void)
 {
     static bool seeded = false;
diff --git a/src/utils/vars/vars.h b/src/utils/vars/vars.h
index 85fb5ee..9e5fa4c 100644
--- a/src/utils/vars/vars.h
+++ b/src/utils/vars/vars.h
@@ -10,11 +10,6 @@
  */
 struct hash_map *vars_init(void);
 
-/**
- * Set default variables.
- */
-void vars_default(struct hash_map *vars);
-
 /**
  * Generate a random short integer (16 bits positive [0-32767]).
  */