diff --git a/minadbd/sockets.c b/minadbd/sockets.c
index 2dd6461..817410d 100644
--- a/minadbd/sockets.c
+++ b/minadbd/sockets.c
@@ -319,7 +319,8 @@
 
         while(avail > 0) {
             r = adb_read(fd, x, avail);
-            D("LS(%d): post adb_read(fd=%d,...) r=%d (errno=%d) avail=%d\n", s->id, s->fd, r, r<0?errno:0, avail);
+            D("LS(%d): post adb_read(fd=%d,...) r=%d (errno=%d) avail=%zu\n",
+              s->id, s->fd, r, r<0?errno:0, avail);
             if(r > 0) {
                 avail -= r;
                 x += r;