diff --git a/kern/libkern/stdio.c b/kern/libkern/stdio.c
index d02e59b..171c8c3 100644
--- a/kern/libkern/stdio.c
+++ b/kern/libkern/stdio.c
@@ -11,6 +11,13 @@ int stdout_puts(char *s, int len, void *unused) {
     return len;
 }
 
+/*
+ * %%       - print '%'
+ * %c       - character
+ * %s       - string
+ * %d, %u   - decimal integer
+ * %x, %X   - hex integer
+ */
 int kprintf(const char *restrict fmt, ...) {
     va_list ap;
     va_start(ap, fmt);