diff --git a/src/ideviceinstaller.c b/src/ideviceinstaller.c
index 6187c97..3762877 100644
--- a/src/ideviceinstaller.c
+++ b/src/ideviceinstaller.c
@@ -643,7 +643,7 @@
 					total += written;
 				}
 				if (total != amount) {
-					fprintf(stderr, "Error: wrote only %d of %d\n", total,
+					fprintf(stderr, "Error: wrote only %d of %zu\n", total,
 							amount);
 					afc_file_close(afc, af);
 					fclose(f);