diff --git a/Makefile b/Makefile
index 9e8ae1a..32b9af2 100644
--- a/Makefile
+++ b/Makefile
@@ -33,10 +33,14 @@ RESET    = "\e[0m"
 # FILES :
 NAME          = computorv1
 D_LIB         = ./libft
-D_SRCS        = ./src
 D_HEADERS     = ./headers
-SRCS          = computorv1.c
-HEADERS       = computorv1.h
+HEADERS       = computorv1.h \
+				errors.h \
+				lexer.h
+D_SRCS        = ./src
+SRCS          = computorv1.c \
+				errors.c \
+				lexer.c
 
 # COMPILATION CONFIG :
 CC            = gcc
@@ -49,7 +53,7 @@ D_OBJS        = builds
 OBJS          = $(SRCS:%.$(EXT)=$(D_OBJS)/%.o)
 VPATH         = $(D_SRCS)
 F_INCLUDES    = $(HEADERS:%=$(D_HEADERS)/%)
-INCLUDES      = -I$(D_HEADERS)
+INCLUDES      = -I$(D_HEADERS) -I$(D_LIB)/includes
 ifeq "$(D_OBJS)" "."
   RM_OBJS     = rm -f $(OBJS)
 else
diff --git a/headers/computorv1.h b/headers/computorv1.h
index f1ed01a..3ed57d7 100644
--- a/headers/computorv1.h
+++ b/headers/computorv1.h
@@ -1,37 +1,6 @@
 #ifndef COMPUTORV1_H
 #define COMPUTORV1_H
 
-#include "../libft/includes/libft.h"
-
-typedef enum
-{
-    ERROR_BASIC,         // 0
-    ERROR_UNKNOWN_TOKEN, // 1
-} program_error;
-
-typedef enum
-{
-    TOKEN_PLUS,           // +
-    TOKEN_MINUS,          // -
-    TOKEN_VARIABLE,       // x, y, etc.
-    TOKEN_NUMBER,         // int or double
-    TOKEN_POWER,          // ^ or **
-    TOKEN_MULTIPLICATION, // *
-    TOKEN_DIVISION,       // /
-    TOKEN_END             // null (end of input)
-} TokenType;
-
-typedef struct
-{
-    TokenType type;
-    union
-    {
-        double num_value; // For NUMBER
-        char var_value;   // For VARIABLE (single char, e.g., 'x')
-    };
-} t_token;
-
-#define MAX_TOKENS 100
-t_token tokens[MAX_TOKENS];
+#include "libft.h"
 
 #endif
\ No newline at end of file
diff --git a/headers/errors.h b/headers/errors.h
new file mode 100644
index 0000000..0f7313b
--- /dev/null
+++ b/headers/errors.h
@@ -0,0 +1,14 @@
+#ifndef ERRORS_H
+#define ERRORS_H
+
+#include "../libft/includes/libft.h"
+
+typedef enum
+{
+    ERROR_BASIC = 0,
+    ERROR_UNKNOWN_TOKEN = -1,
+} program_error;
+
+int stop_errors(int err);
+
+#endif
\ No newline at end of file
diff --git a/headers/lexer.h b/headers/lexer.h
new file mode 100644
index 0000000..7e7da5d
--- /dev/null
+++ b/headers/lexer.h
@@ -0,0 +1,31 @@
+#ifndef LEXER_H
+#define LEXER_H
+
+#include "../libft/includes/libft.h"
+
+typedef enum
+{
+    TOKEN_PLUS,           // +
+    TOKEN_MINUS,          // -
+    TOKEN_VARIABLE,       // x, y, etc.
+    TOKEN_NUMBER,         // int or double
+    TOKEN_POWER,          // ^ or **
+    TOKEN_MULTIPLICATION, // *
+    TOKEN_DIVISION,       // /
+    TOKEN_END             // null (end of input)
+} token_type;
+
+typedef struct
+{
+    token_type type;
+    union
+    {
+        double num_value; // For NUMBER
+        char var_value;   // For VARIABLE (single char, e.g., 'x')
+    };
+} token;
+
+#define MAX_TOKENS 100
+int lexerize(const char *input, token tokens[MAX_TOKENS]);
+
+#endif
\ No newline at end of file
diff --git a/src/computorv1.c b/src/computorv1.c
index b495bc6..46326b6 100644
--- a/src/computorv1.c
+++ b/src/computorv1.c
@@ -1,71 +1,6 @@
-
 #include "computorv1.h"
-
-int stop_errors(int err)
-{
-    switch (err)
-    {
-    case -ERROR_UNKNOWN_TOKEN:
-        ft_putstr_fd("error: unknown token\n", STDERR_FILENO);
-        break;
-
-    default:
-        ft_putstr_fd("unknown error\n", STDERR_FILENO);
-        break;
-    }
-
-    exit(err);
-}
-
-int skip_whitespace(const char *input, int input_pos)
-{
-    while (ft_isspace(input[input_pos]))
-    {
-        input_pos++;
-    }
-    return input_pos;
-}
-
-int token_is_plus(const char *input, int input_pos)
-{
-    return (input[input_pos] == '+');
-}
-
-int lexerize(const char *input)
-{
-    int token_count = 0;
-    int input_pos = 0;
-    int token_size = 0;
-
-    while (input[input_pos])
-    {
-        input_pos = skip_whitespace(input, input_pos);
-
-        if (input[input_pos] == '\0')
-        {
-            break;
-        }
-
-        token_size = token_is_plus(input, input_pos);
-        if (token_size)
-        {
-            tokens[token_count].type = TOKEN_PLUS;
-            tokens[token_count].var_value = '+';
-        }
-
-        if (token_size == 0)
-        {
-            stop_errors(-ERROR_UNKNOWN_TOKEN);
-        }
-        token_count++;
-        input_pos += token_size;
-    }
-
-    // Add end token
-    tokens[token_count].type = TOKEN_END;
-    tokens[token_count].var_value = '\0';
-    return 1;
-}
+#include "lexer.h"
+#include "errors.h"
 
 int main(int ac, char **av)
 {
@@ -86,7 +21,8 @@ int main(int ac, char **av)
         i++;
     }
 
-    ret = lexerize(av[1]);
+    token tokens[MAX_TOKENS];
+    ret = lexerize(av[1], tokens);
     if (ret <= 0)
     {
         stop_errors(ret);
diff --git a/src/errors.c b/src/errors.c
new file mode 100644
index 0000000..2ffb257
--- /dev/null
+++ b/src/errors.c
@@ -0,0 +1,17 @@
+#include "errors.h"
+
+int stop_errors(int err)
+{
+    switch (err)
+    {
+    case ERROR_UNKNOWN_TOKEN:
+        ft_putstr_fd("error: unknown token\n", STDERR_FILENO);
+        break;
+
+    default:
+        ft_putstr_fd("unknown error\n", STDERR_FILENO);
+        break;
+    }
+
+    exit(err);
+}
\ No newline at end of file
diff --git a/src/lexer.c b/src/lexer.c
new file mode 100644
index 0000000..e6fcb0b
--- /dev/null
+++ b/src/lexer.c
@@ -0,0 +1,52 @@
+#include "lexer.h"
+#include "errors.h"
+
+static int skip_whitespace(const char *input, int input_pos)
+{
+    while (ft_isspace(input[input_pos]))
+    {
+        input_pos++;
+    }
+    return input_pos;
+}
+
+static int token_is_plus(const char *input, int input_pos)
+{
+    return (input[input_pos] == '+');
+}
+
+int lexerize(const char *input, token tokens[MAX_TOKENS])
+{
+    int token_count = 0;
+    int input_pos = 0;
+    int token_size = 0;
+
+    while (input[input_pos])
+    {
+        input_pos = skip_whitespace(input, input_pos);
+
+        if (input[input_pos] == '\0')
+        {
+            break;
+        }
+
+        token_size = token_is_plus(input, input_pos);
+        if (token_size)
+        {
+            tokens[token_count].type = TOKEN_PLUS;
+            tokens[token_count].var_value = '+';
+        }
+
+        if (token_size == 0)
+        {
+            stop_errors(ERROR_UNKNOWN_TOKEN);
+        }
+        token_count++;
+        input_pos += token_size;
+    }
+
+    tokens[token_count].type = TOKEN_END;
+    tokens[token_count].var_value = '\0';
+
+    return 1;
+}