diff --git a/runtest.c b/runtest.c
index 1861577..b2ce693 100644
--- a/runtest.c
+++ b/runtest.c
@@ -688,7 +688,7 @@
     }
     if (info.st_size != size) {
         fprintf(stderr, "file %s is %ld bytes, result is %d bytes\n",
-	        filename, info.st_size, size);
+	        filename, (long) info.st_size, size);
         return(-1);
     }
     fd = open(filename, RD_FLAGS);