diff --git a/src/Makefile b/src/Makefile
index b4062eb..d9df561 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -16,6 +16,7 @@ OBJS	= \
 	  paging.o \
 	  elf.o \
 	  myfile.o \
+	  tools.o \
 
 DEPS = $(OBJS:.o=.d)
 
diff --git a/src/debug.c b/src/debug.c
index 4770ffd..0d0453d 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -19,7 +19,7 @@ int print_variadic(char *msg, va_list args)
                 write_serial(va_arg(args, char *));
                 break;
             case 'b':
-                write_serial_bin(va_arg(args, char *), false);
+                write_serial_bin((int) va_arg(args, char *), false);
                 break;
             case 'c':
                 write_serial_char(va_arg(args, int));
@@ -36,12 +36,14 @@ int print_variadic(char *msg, va_list args)
             msg++;
         }
     }
+
+    return 0;
 }
 
-int debug_info(char *fnt, char *msg, ...)
+int debug_info(const char *fnt, char *msg, ...)
 {
     write_serial("\033[0;34m[INFO]\033[0m     ");
-    write_serial(fnt);
+    write_serial((char *) fnt);
     write_serial("\t: ");
 
     va_list args;
@@ -54,10 +56,10 @@ int debug_info(char *fnt, char *msg, ...)
     return 0;
 }
 
-int debug_warn(char *fnt, char *msg, ...)
+int debug_warn(const char *fnt, char *msg, ...)
 {
     write_serial("\033[0;33m[WARNING]\033[0m  ");
-    write_serial(fnt);
+    write_serial((char *) fnt);
     write_serial("\t: ");
     
     va_list args;
@@ -70,10 +72,10 @@ int debug_warn(char *fnt, char *msg, ...)
     return 0;
 }
 
-int debug_err(char *fnt, char *msg, ...)
+int debug_err(const char *fnt, char *msg, ...)
 {
     write_serial("\033[0;31m[ERROR]\033[0m    ");
-    write_serial(fnt);
+    write_serial((char *) fnt);
     write_serial("\t: ");
 
     va_list args;
diff --git a/src/debug.h b/src/debug.h
index 02f4b49..021f92e 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -15,8 +15,8 @@
 	#define DEBUG_ERR(...)
 #endif
 
-int debug_info(char *fnt, char *msg, ...);
-int debug_warn(char *fnt, char *msg, ...);
-int debug_err(char *fnt, char *msg, ...);
+int debug_info(const char *fnt, char *msg, ...);
+int debug_warn(const char *fnt, char *msg, ...);
+int debug_err(const char *fnt, char *msg, ...);
 
 #endif /*   DEBUG_H */
diff --git a/src/elf.c b/src/elf.c
index ff050fe..c453b8d 100644
--- a/src/elf.c
+++ b/src/elf.c
@@ -4,6 +4,7 @@
 #include "serial.h"
 #include "debug.h"
 #include "paging.h"
+#include "tools.h"
 
 int load_elf(char *elf_data_start, int uid)
 {
@@ -29,13 +30,15 @@ int load_elf(char *elf_data_start, int uid)
 				allocate_new_page(uid, mem << 12);
 			}
 
-			memcpy(elf_header_table->p_vaddr, elf_data_start + elf_header_table->p_offset, elf_header_table->p_filesz);
+			memcpy((void *) elf_header_table->p_vaddr, elf_data_start + elf_header_table->p_offset, elf_header_table->p_filesz);
 
 			if (elf_header_table->p_filesz < elf_header_table->p_memsz)
 			{
-				for (int i = elf_header_table->p_filesz; i < elf_header_table->p_memsz; i++)
+				for (u32 i = elf_header_table->p_filesz; i < elf_header_table->p_memsz; i++)
 					elf_header_table->p_vaddr[elf_data_start + elf_header_table->p_offset + i] = 0;
 			}
 		}
 	}
+
+	return 0;
 }
diff --git a/src/elf.h b/src/elf.h
index 680a912..8ba155d 100644
--- a/src/elf.h
+++ b/src/elf.h
@@ -48,4 +48,4 @@ enum elf_segment_type {
 
 int load_elf(char *elf_data_start, int uid);
 
-#endif ELF_H
+#endif /*   !ELF_H */
diff --git a/src/gdt.c b/src/gdt.c
index 3864ce7..43a60fb 100644
--- a/src/gdt.c
+++ b/src/gdt.c
@@ -8,19 +8,6 @@
 #include "tss.h"
 #include "userland.h"
 
-void *memcpy(void *dest, const void *src, size_t n)
-{
-	const char *s = src;
-	char *d = dest;
-
-	for (size_t i = 0; i < n; i++)
-    {
-		*d++ = *s++;
-    }
-
-	return dest;
-}
-
 struct tss user_land_tss;
 
 struct segment_desc_param {
@@ -66,8 +53,9 @@ void init_gdt(void)
 {
     DEBUG_INFO("Initializing GDT");
 
+    u16 gdt_size = sizeof(gdt) / sizeof(struct segdesc);
     DEBUG_INFO("GDT BASE ADDRESS: %d", (u32) &kgdtr);
-    DEBUG_INFO("GDT LIMIT: %d", sizeof(gdt) - 1);
+    DEBUG_INFO("GDT LIMIT: %d", gdt_size - 1);
     kgdtr.limit     = sizeof(gdt) - 1;
     kgdtr.base      = (u32) gdt;
 
@@ -102,10 +90,10 @@ void init_gdt(void)
     DEBUG_INFO("TSS BASE ADDRESS: %d", (u32) &user_land_tss);
 
     gdt[5] = init_descriptor((struct segment_desc_param) { .Limit_1 = sizeof(user_land_tss),
-                            .Base = &user_land_tss, .Type = 0x09, .S = 0, .DPL = 3, .P = 1,
+                            .Base = (u32) &user_land_tss, .Type = 0x09, .S = 0, .DPL = 3, .P = 1,
                             .Limit_2 = 0x00, .AVL = 0, .L = 0, .D_B = 0, .G = 0 });
 
-    for (int i = 0; i < sizeof(gdt) / 8; i++)
+    for (size_t i = 0; i < gdt_size; i++)
     {
         char *ptr = (char *) &gdt[i];
         DEBUG_INFO("--------------------");
diff --git a/src/gdt.h b/src/gdt.h
index beb2f3f..2070f21 100644
--- a/src/gdt.h
+++ b/src/gdt.h
@@ -27,4 +27,4 @@ struct segdesc {
 void init_gdt(void);
 void temp_run_process(void);
 
-#endif				/* !GDT_H */
\ No newline at end of file
+#endif /*       !GDT_H */
\ No newline at end of file
diff --git a/src/idt.c b/src/idt.c
index 6d57aa3..f5a0bdf 100644
--- a/src/idt.c
+++ b/src/idt.c
@@ -46,8 +46,9 @@ struct idt_segdesc init_gate(struct interrupt_gate_param param)
 
     descriptor.Type         =       param.Type | (param.D << 3);
 
-    descriptor.Flags        |=       param.DPL << 1;
-    descriptor.Flags        |=       param.P << 3;
+    descriptor.Flags        =       0;
+    descriptor.Flags        |=      param.DPL << 1;
+    descriptor.Flags        |=      param.P << 3;
 
     return descriptor;
 }
@@ -56,12 +57,13 @@ void init_idt(void)
 {
     DEBUG_INFO("Initializing IDT");
 
+    u16 idt_size = sizeof(idt) / sizeof(struct idt_segdesc);
     DEBUG_INFO("IDT BASE ADDRESS: %d", (u32) &kidtr);
-    DEBUG_INFO("IDT LIMIT: %d", sizeof(idt) - 1);
+    DEBUG_INFO("IDT LIMIT: %d", idt_size - 1);
     kidtr.limit     = sizeof(idt) - 1;
     kidtr.base      = (u32) idt;
     
-    for (int i = 0; i < sizeof(idt); i++)
+    for (size_t i = 0; i < idt_size; i++)
     {
         idt[i] = init_gate((struct interrupt_gate_param) { .Offset = (u32) _asm_default_int, .SegSelect = 0x08,
         .Type = 0x06, .D = 1, .DPL = 0, .P = 1 });
diff --git a/src/kernel.c b/src/kernel.c
index e31e104..b314a03 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -18,9 +18,7 @@ void main(void)
 {
 	DEBUG_INFO("Entering Main Function");
 
-	char *data_start     = &_binary_a_out_start;
-    char *data_end       = _binary_a_out_end;
-    size_t data_size  = (size_t)_binary_a_out_size;
+	char *data_start	= (char *) &_binary_a_out_start;
 
 	create_process(0, data_start);
 	switch_to_process(0);
diff --git a/src/launch_process.c b/src/launch_process.c
index 18ca823..1e76060 100644
--- a/src/launch_process.c
+++ b/src/launch_process.c
@@ -3,7 +3,7 @@
 #include "tss.h"
 #include "debug.h"
 
-void launch_process(u16 tss, int memory_start, int userland_stack, int userland_code, u16 userland_data)
+void launch_process(u16 tss, int userland_stack, int userland_code, u16 userland_data)
 {
     // Setting DPL and GDT bits
     userland_stack += 3;
diff --git a/src/launch_process.h b/src/launch_process.h
index 7074392..936d87c 100644
--- a/src/launch_process.h
+++ b/src/launch_process.h
@@ -3,6 +3,6 @@
 
 #include <types.h>
 
-void launch_process(u16 tss, int memory_start, int userland_stack, int userland_code, u16 userland_data);
+void launch_process(u16 tss, int userland_stack, int userland_code, u16 userland_data);
 
 #endif /*   !LAUNCH_PROCESS_H */
\ No newline at end of file
diff --git a/src/paging.c b/src/paging.c
index f302fb2..7902f32 100644
--- a/src/paging.c
+++ b/src/paging.c
@@ -124,7 +124,7 @@ int create_kernel_page(void)
         DEBUG_INFO("PAGE_TABLE %d", &page_table[i * 1024]);
         page_dir[i] = create_page_directory_entry((struct page_directory_param) {
                     .P = 1, .R_W = 1, .U = 0, .PWT = 0, .PCD = 0,
-                    .A = 0, .PS = 0, .address = &page_table[i * 1024]});
+                    .A = 0, .PS = 0, .address = (u32) &page_table[i * 1024]});
     }
 
     for (int i = NB_KERNEL_PAGE_DIR; i < 1024; i++)
@@ -193,7 +193,7 @@ int create_new_userland_page(int uid)
         DEBUG_INFO("PAGE_TABLE %d", &kernel_page_table[i * 1024]);
         userland_page_dir[i] = create_page_directory_entry((struct page_directory_param) {
                         .P = 1, .R_W = 1, .U = 0, .PWT = 0, .PCD = 0,
-                        .A = 0, .PS = 0, .address = &kernel_page_table[i * 1024]});
+                        .A = 0, .PS = 0, .address = (u32) &kernel_page_table[i * 1024]});
     }
 
     for (int i = 0; i < 1024; i++)
@@ -208,7 +208,7 @@ int create_new_userland_page(int uid)
 
     userland_page_dir[NB_KERNEL_PAGE_DIR] = create_page_directory_entry((struct page_directory_param) {
                         .P = 1, .R_W = 1, .U = 0, .PWT = 0, .PCD = 0,
-                        .A = 0, .PS = 0, .address = userland_data->userland_data[uid].page_table});
+                        .A = 0, .PS = 0, .address = (u32) userland_data->userland_data[uid].page_table});
 
     for (int i = NB_KERNEL_PAGE_DIR + 1; i < 1024; i++)
     {
@@ -216,6 +216,8 @@ int create_new_userland_page(int uid)
                         .P = 0, .R_W = 0, .U = 0, .PWT = 0, .PCD = 0,
                         .A = 0, .PS = 0, .address = 0});
     }
+
+    return 0;
 }
 
 int allocate_new_page(int uid, int address)
@@ -231,7 +233,7 @@ int allocate_new_page(int uid, int address)
     // CPU does't use page table when decoding page table, so it need the physical address
     int new_page_table_real = (int) userland_data->userland_data[uid].page_table[dir_address].address;
     DEBUG_INFO("PAGE TABLE REAL ADDRESS %d", new_page_table_real << 12);
-    struct page_table_entry *new_page_table = USERLAND_BASE_ADDRESS + dir_address * 1024 * 4 + table_address * 4;
+    struct page_table_entry *new_page_table = (struct page_table_entry *) (USERLAND_BASE_ADDRESS + dir_address * 1024 * 4 + table_address * 4);
 
     if (userland_page_dir[dir_address].address != 0 && new_page_table->address != 0)
         clear_page(new_page_table->address);
@@ -250,4 +252,6 @@ int allocate_new_page(int uid, int address)
                         .P = 1, .R_W = 1, .U = 1, .PWT = 0, .PCD = 0,
                         .A = 0, .D = 0, .PAT = 0, .G = 0,
                         .address = (avl_address >> 12)});
+    
+    return 0;
 }
diff --git a/src/paging.h b/src/paging.h
index ebb0857..fbbd022 100644
--- a/src/paging.h
+++ b/src/paging.h
@@ -17,6 +17,7 @@ struct page_table_entry {
 } __attribute__((packed));
 
 int create_kernel_page(void);
+int create_new_userland_page(int uid);
 int allocate_new_page(int uid, int address);
 
 // extern struct page_directory_entry page_dir[1024];
diff --git a/src/serial.c b/src/serial.c
index 143a771..5e530e4 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -20,6 +20,8 @@ int init_serial()
 	outb(PORT + 3, 0x03);    // 8 bits, no parity, one stop bit
 	outb(PORT + 2, 0xC7);    // Enable FIFO, clear them, with 14-byte threshold
 	outb(PORT + 4, 0x0B);    // IRQs enabled, RTS/DSR set
+
+	return 0;
 }
 
 int write_serial_nb(int nb, int ln)
@@ -86,7 +88,7 @@ int write_serial_char(char c)
 
 int write_serial(char * s)
 {
-	for (size_t i = 0; i < strlen(s); i++)
+	for (int i = 0; i < strlen(s); i++)
 	{
 		while ((inb(PORT + 5) & 0x20) == 0);
 		outb(PORT, s[i]);
diff --git a/src/tools.c b/src/tools.c
new file mode 100644
index 0000000..15e8f77
--- /dev/null
+++ b/src/tools.c
@@ -0,0 +1,14 @@
+#include "tools.h"
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	const char *s = src;
+	char *d = dest;
+
+	for (size_t i = 0; i < n; i++)
+    {
+		*d++ = *s++;
+    }
+
+	return dest;
+}
diff --git a/src/tools.h b/src/tools.h
new file mode 100644
index 0000000..952f7fe
--- /dev/null
+++ b/src/tools.h
@@ -0,0 +1,8 @@
+#ifndef TOOLS_H
+#define TOOLS_H
+
+#include <types.h>
+
+void *memcpy(void *dest, const void *src, size_t n);
+
+#endif /*   !TOOLS_H */
diff --git a/src/userland.c b/src/userland.c
index e154f90..f3561b9 100644
--- a/src/userland.c
+++ b/src/userland.c
@@ -2,9 +2,10 @@
 
 #include "debug.h"
 #include "paging.h"
+#include "elf.h"
 #include "launch_process.h"
 
-struct userlands_data *userland_data = 0x3020000;
+struct userlands_data *userland_data = (struct userlands_data *) 0x3020000;
 
 int create_process(int uid, char *data_start)
 {
@@ -41,5 +42,7 @@ int switch_to_process(int uid)
         mov %%eax, %%cr3" : "+r" (process_page_dir_adress));
 
     // TODO : once data by process has been implemented, load the right one
-    launch_process(0x28, 0x6000000, 0x20, 0x18, 0x20);
+    launch_process(0x28, 0x20, 0x18, 0x20);
+
+    return 0;
 }