diff --git a/src/kernel.c b/src/kernel.c
index 31ef846..ea048b4 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -8,12 +8,10 @@
 void kmain()
 {
     vga_clear();
-
     pic_remap();
     enable_interrupts();
 
-    kprintf("\nWelcome to nub OS\n");
-
+    kprintf("Welcome to nub OS\n");
     khalt();
 }
 
@@ -28,12 +26,18 @@ void kprintf(const char* fmt, ...)
     va_list args;
     va_start(args, fmt);
 
+    bool should_format = false;
+
     for (size_t i = 0; fmt[i] != '\0'; i++)
     {
-        if (fmt[i] == '%')
+        if (should_format)
         {
-            i++;
-            if (fmt[i] == 's')
+            should_format = false;
+            if (fmt[i] == '%')
+            {
+                vga_put_char('%', 0x0F);
+            }
+            else if (fmt[i] == 's')
             {
                 const char* str = va_arg(args, const char*);
                 for (size_t j = 0; str[j] != '\0'; j++)
@@ -43,20 +47,29 @@ void kprintf(const char* fmt, ...)
             }
             else if (fmt[i] == 'd')
             {
-                int val = va_arg(args, int);
-                char buf[12];
-                itoa(val, buf);
+                int64_t val = va_arg(args, int64_t);
+                char buf[21];
+                itoa64(val, buf);
                 for (size_t j = 0; buf[j] != '\0'; j++)
                 {
                     vga_put_char(buf[j], 0x0F);
                 }
             }
-            else
+            else if (fmt[i] == 'u')
             {
-                vga_put_char('%', 0x0F);
-                vga_put_char(fmt[i], 0x0F);
+                uint64_t val = va_arg(args, uint64_t);
+                char buf[21];
+                uitoa64(val, buf);
+                for (size_t j = 0; buf[j] != '\0'; j++)
+                {
+                    vga_put_char(buf[j], 0x0F);
+                }
             }
         }
+        else if (fmt[i] == '%')
+        {
+            should_format = true;
+        }
         else
         {
             vga_put_char(fmt[i], 0x0F);
diff --git a/src/string.c b/src/string.c
index 01ab9b5..9d2492d 100644
--- a/src/string.c
+++ b/src/string.c
@@ -25,64 +25,77 @@ void reverse(char* str, size_t length)
     }
 }
 
-int uitoa(uint64_t value, char* buffer)
+void itoa64(int64_t value, char* buffer)
 {
-    int i = 0;
-    if (value == 0)
-    {
-        buffer[i++] = '0';
-        buffer[i] = '\0';
-        return i;
-    }
-
-    while (value > 0)
-    {
-        buffer[i++] = (value % 10) + '0';
-        value /= 10;
-    }
-
-    buffer[i] = '\0';
-    reverse(buffer, i);
-    return i;
-}
-
-int itoa(int64_t value, char* buffer)
-{
-    int i = 0;
-
-    if (value == 0)
-    {
-        buffer[i++] = '0';
-        buffer[i] = '\0';
-        return i;
-    }
-
-    bool negative = false;
-    uint64_t v;
+    char temp[21];
+    int i = 0, j = 0;
+    int negative = 0;
 
     if (value < 0)
     {
-        negative = true;
-        v = (uint64_t)(-value);
-    }
-    else
-    {
-        v = (uint64_t)value;
+        negative = 1;
+        if (value == INT64_MIN)
+        {
+            const char* min_str = "9223372036854775808";
+            for (i = 0; min_str[i] != '\0'; i++)
+                temp[i] = min_str[i];
+            i = 19;
+        }
+        else
+        {
+            value = -value;
+        }
     }
 
-    while (v > 0)
+    if (value == 0 && !negative)
     {
-        buffer[i++] = (v % 10) + '0';
-        v /= 10;
+        buffer[0] = '0';
+        buffer[1] = '\0';
+        return;
+    }
+
+    if (!(negative && value == INT64_MIN))
+    {
+        while (value > 0)
+        {
+            temp[i++] = '0' + (value % 10);
+            value /= 10;
+        }
     }
 
     if (negative)
     {
-        buffer[i++] = '-';
+        temp[i++] = '-';
     }
 
-    buffer[i] = '\0';
-    reverse(buffer, i);
+    while (i > 0)
+    {
+        buffer[j++] = temp[--i];
+    }
+    buffer[j] = '\0';
+}
 
-    return i;
+void uitoa64(uint64_t value, char* buffer)
+{
+    char temp[21];
+    int i = 0, j = 0;
+
+    if (value == 0)
+    {
+        buffer[0] = '0';
+        buffer[1] = '\0';
+        return;
+    }
+
+    while (value > 0)
+    {
+        temp[i++] = '0' + (value % 10);
+        value /= 10;
+    }
+
+    while (i > 0)
+    {
+        buffer[j++] = temp[--i];
+    }
+    buffer[j] = '\0';
 }
\ No newline at end of file
diff --git a/src/string.h b/src/string.h
index 49ed2aa..1abefcf 100644
--- a/src/string.h
+++ b/src/string.h
@@ -5,5 +5,5 @@
 
 int strcmp(const char* a, const char* b);
 void reverse(char* str, size_t length);
-int uitoa(uint64_t value, char* buffer);
-int itoa(int64_t value, char* buffer);
\ No newline at end of file
+void uitoa64(uint64_t value, char* buffer);
+void itoa64(int64_t value, char* buffer);
\ No newline at end of file