diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c
index d9a6e3e556..d67953a1c3 100644
--- a/subprojects/libvhost-user/libvhost-user.c
+++ b/subprojects/libvhost-user/libvhost-user.c
@@ -700,7 +700,7 @@ vu_add_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
     if (vmsg->size < VHOST_USER_MEM_REG_SIZE) {
         close(vmsg->fds[0]);
         vu_panic(dev, "VHOST_USER_ADD_MEM_REG requires a message size of at "
-                      "least %d bytes and only %d bytes were received",
+                      "least %zu bytes and only %d bytes were received",
                       VHOST_USER_MEM_REG_SIZE, vmsg->size);
         return false;
     }
@@ -826,7 +826,7 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
     if (vmsg->size < VHOST_USER_MEM_REG_SIZE) {
         vmsg_close_fds(vmsg);
         vu_panic(dev, "VHOST_USER_REM_MEM_REG requires a message size of at "
-                      "least %d bytes and only %d bytes were received",
+                      "least %zu bytes and only %d bytes were received",
                       VHOST_USER_MEM_REG_SIZE, vmsg->size);
         return false;
     }