diff --git a/Monicelli.ll b/Monicelli.ll
index 12a8c82..9d69e7d 100644
--- a/Monicelli.ll
+++ b/Monicelli.ll
@@ -1,7 +1,8 @@
 %{
 #include "Monicelli.tab.h"
-#include <stdlib.h>
-#include <stdio.h>
+
+#include <string>
+#include <cstdlib>
 
 extern int lineNumber;
 
@@ -163,7 +164,7 @@ CHAR  [a-zA-Z_]
 <INITIAL,shift>[ \t\f\v] {}
 
 {CHAR}({DIGIT}|{CHAR})* {
-    mclval.strval = strdup(yytext);
+    mclval.strval = new std::string(yytext);
     return ID;
 } 
 
diff --git a/Monicelli.y b/Monicelli.y
index 5471f84..7e014db 100644
--- a/Monicelli.y
+++ b/Monicelli.y
@@ -6,9 +6,6 @@ extern int yylex();
 
 #include "Nodes.hpp"
 
-// For free()
-#include <cstdlib>
-
 using namespace monicelli;
 
 extern Program *program;
@@ -53,7 +50,7 @@ static std::stack<BranchCaseList*> branchCaseStack;
 %union {
     int intval;
     double floatval;
-    char *strval;
+    std::string* strval;
     bool boolval;
     monicelli::Type typeval;
     monicelli::Statement* statementval;
@@ -131,7 +128,6 @@ fun_decl:
         $$ = new Function(new Id($2), paramsStack.top(), stmtStack.top());
         paramsStack.pop();
         stmtStack.pop();
-        free($2);
     }
 ;
 args:
@@ -195,11 +191,9 @@ numeric:
 variable:
     ID {
         $$ = new Id($1);
-        free($1);
     }
     | ARTICLE ID {
         $$ = new Id($2);
-        free($2);
     }
 ;
 assign_stmt:
@@ -273,7 +267,6 @@ fun_call:
     ID call_args FUN_END {
         $$ = new FunctionCall(new Id($3), argsStack.top());
         argsStack.pop();
-        free($3);
     }
 ;
 call_args:
diff --git a/Nodes.cpp b/Nodes.cpp
index d1db6b0..6b85e04 100644
--- a/Nodes.cpp
+++ b/Nodes.cpp
@@ -11,7 +11,7 @@ void emitIndent(std::ostream &stream, int indent) {
 }
 
 void Id::emit(std::ostream &stream, int indent) {
-    stream << value;
+    stream << *value;
 }
 
 void Integer::emit(std::ostream &stream, int indent) {
diff --git a/Nodes.hpp b/Nodes.hpp
index 2bcab38..e51db20 100644
--- a/Nodes.hpp
+++ b/Nodes.hpp
@@ -90,13 +90,13 @@ class SimpleExpression: public Expression {
 
 class Id: public SimpleExpression {
 public:
-    explicit Id(const char *c): value(c) {}
+    explicit Id(std::string *c): value(c) {}
     virtual ~Id() {}
 
     virtual void emit(std::ostream &stream, int indent = 0);
 
 private:
-    std::string value;
+    std::unique_ptr<std::string> value;
 };