diff --git a/src/main.c b/src/main.c
index 5775196..91170e4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -112,7 +112,7 @@
 
 	for (size_t i = 0; i < (size_t)(read + 15) / 16 * 16; ++i) {
 		if (i % 16 == 0)
-			printf("%06x:  ", i);
+			printf("%06zx:  ", i);
 		else if (i % 8 == 0)
 			printf(" ");
 		if (i < read)