diff --git a/gdbstub.c b/gdbstub.c
index 813502f368..79f54f51f9 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -929,7 +929,8 @@ static void gdb_vm_stopped(void *opaque, int reason)
 
     if (reason == EXCP_DEBUG) {
         if (s->env->watchpoint_hit) {
-            snprintf(buf, sizeof(buf), "T%02xwatch:%x;", SIGTRAP,
+            snprintf(buf, sizeof(buf), "T%02xwatch:" TARGET_FMT_lx ";",
+                     SIGTRAP,
                      s->env->watchpoint[s->env->watchpoint_hit - 1].vaddr);
             put_packet(s, buf);
             s->env->watchpoint_hit = 0;