diff --git a/Makefile b/Makefile
index 69b960b..19bc3ee 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-g -Wall
+CFLAGS=-g -Wall -Iinclude
 SRC=src
 OBJ=obj
 SRCS=$(wildcard $(SRC)/*.c)
diff --git a/blank16sectorcard b/blank16sectorcard
index 1ac1d2a..cafae06 100644
Binary files a/blank16sectorcard and b/blank16sectorcard differ
diff --git a/include/modifyUID.h b/include/modifyUID.h
new file mode 100644
index 0000000..99b5dcd
--- /dev/null
+++ b/include/modifyUID.h
@@ -0,0 +1,4 @@
+#include <stdio.h>
+#include "colors.h"
+
+void modifyUID(FILE *file);
diff --git a/makefile b/makefile
deleted file mode 100644
index 89899d8..0000000
--- a/makefile
+++ /dev/null
@@ -1,19 +0,0 @@
-CC = gcc
-CFLAGS = -Wall -I$(INCLUDE)
-INCLUDE = include
-SRC_DIR = src
-OBJ_DIR = obj
-SRC = $(wildcard $(SRC_DIR)/*.c)
-OBJ = $(patsubst $(SRC_DIR)/%.c, $(OBJ_DIR)/%.o, $(SRC))
-BIN = ./main
-
-all: $(BIN)
-
-$(BIN): $(OBJ)
-	$(CC) -o $@ $^
-
-$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c MKOBJ
-	$(CC) $(CFLAGS) -c $< -o $@
-
-clean:
-	rm -f $(OBJ_DIR)/*.o $(BIN)
diff --git a/src/getSize.c b/src/getSize.c
index cfd274e..795757d 100644
--- a/src/getSize.c
+++ b/src/getSize.c
@@ -5,7 +5,7 @@
 void getSize(FILE *file, int argc, char *argv[]) {
   fseek(file, 0L, SEEK_END);
   long bytes = ftell(file);
-  fseek(file, 0L, SEEK_SET);
+  rewind(file); // <== Same as `fseek(file, 0L, SEEK_SET)`;
   if (bytes == 1024) {
     printf("Bytes of %s: %ld\n", argv[argc - 1], bytes);
     puts("This looks like a Mifare Classic 1K dump file");
diff --git a/src/main.c b/src/main.c
index 676be69..7ec0fdb 100644
--- a/src/main.c
+++ b/src/main.c
@@ -6,28 +6,35 @@
 
 #include "getSize.h"
 #include "readFile.h"
+#include "modifyUID.h"
 
 int main(int argc, char *argv[]) {
 
-	if (argv[argc] == 1) { 
+	if (argc <= 1) {
+		puts("Please, specify a file next to the executable\n");
+		printf("Example:\n\t%s [file]\n", argv[0]);
+		exit(EXIT_SUCCESS);
+	}
 
+	FILE *file;
+	char *binfile = malloc(64 * sizeof(char));
+	if (binfile == NULL) {
+		puts("Failed to allocate memory");
+		exit(EXIT_FAILURE);
+	}
 
-  FILE *file;
-  char *binfile = malloc(64 * sizeof(char));
-  if (binfile == NULL) {
-    puts("Failed to allocate memory");
-    exit(EXIT_FAILURE);
-  }
+	file = fopen(argv[argc - 1], "r+b");
+	if (file == NULL) {
+		perror("Error while opening the file");
+		exit(EXIT_FAILURE);
+	}
 
-  file = fopen(argv[argc - 1], "rb");
-  if (file == NULL) {
-    perror("Error while opening the file");
-    exit(EXIT_FAILURE);
-  }
+	// readFile(file);
+	// getSize(file, argc, argv);
+	modifyUID(file);
+	
 
-  readFile(file);
-
-  fclose(file);
-  free(binfile);
-  exit(EXIT_SUCCESS);
+	fclose(file);
+	free(binfile);
+	exit(EXIT_SUCCESS);
 }
diff --git a/src/modifyUID.c b/src/modifyUID.c
new file mode 100644
index 0000000..2138444
--- /dev/null
+++ b/src/modifyUID.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include "colors.h"
+
+void modifyUID(FILE *file) {
+	fseek(file, 0, SEEK_SET);
+	unsigned char newByte = 0x67;
+	fwrite(&newByte, sizeof(newByte), 1, file);
+}