diff --git a/Internal.h b/Internal.h
index 6e1749e..58464bd 100644
--- a/Internal.h
+++ b/Internal.h
@@ -5,6 +5,7 @@
 #include <assert.h>
 #include <bit>
 #include <span>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <utility>