diff --git a/src/print.c b/src/print.c
index e7e9e71..4f1dc7c 100644
--- a/src/print.c
+++ b/src/print.c
@@ -214,7 +214,7 @@ int patty_print_hexdump(FILE *fh, void *data, size_t len) {
     for (i=0; i<len; i+=16) {
         size_t x;
 
-        if (fprintf(fh, "%08lx:", i) < 0) {
+        if (fprintf(fh, "%08zx:", i) < 0) {
             goto error_io;
         }