diff --git a/timethem.c b/timethem.c
index d28a797..3f8f493 100644
--- a/timethem.c
+++ b/timethem.c
@@ -87,7 +87,7 @@ int main(int argc, char **argv) {
     }
     for (int i = 1; i < argc; i++) {
         resultT m = median(results[i], N);
-        printf("%-20s %8.3f ms %2d bytes\n", argv[i], m.time / 1E6, m.nread);
+        printf("%-20s %8.3f ms %2zd bytes\n", argv[i], m.time / 1E6, m.nread);
     }
     return 0;
 }