diff --git a/ui/vnc.c b/ui/vnc.c
index 548588aab89ee2c71a5033ad657aa4dce6ed46ad..f8d9b7db9571e04cf4fd361853ac205f470f4be2 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -887,6 +887,7 @@ static int find_and_clear_dirty_height(struct VncState *vs,
 
 static int vnc_update_client(VncState *vs, int has_dirty, bool sync)
 {
+    vs->has_dirty += has_dirty;
     if (vs->need_update && vs->csock != -1) {
         VncDisplay *vd = vs->vd;
         VncJob *job;
@@ -898,7 +899,7 @@ static int vnc_update_client(VncState *vs, int has_dirty, bool sync)
             /* kernel send buffers are full -> drop frames to throttle */
             return 0;
 
-        if (!has_dirty && !vs->audio_cap && !vs->force_update)
+        if (!vs->has_dirty && !vs->audio_cap && !vs->force_update)
             return 0;
 
         /*
@@ -941,6 +942,7 @@ static int vnc_update_client(VncState *vs, int has_dirty, bool sync)
             vnc_jobs_join(vs);
         }
         vs->force_update = 0;
+        vs->has_dirty = 0;
         return n;
     }
 
@@ -1878,6 +1880,7 @@ static void framebuffer_update_request(VncState *vs, int incremental,
         return;
     }
 
+    vs->force_update = 1;
     vnc_set_area_dirty(vs->dirty, width, height, x, y, w, h);
 }
 
diff --git a/ui/vnc.h b/ui/vnc.h
index 8f582fdc6cd669d18e3b2dd8b9782d64aa5cf694..334de9ddb1ba823d2b7e092ce20bdf3bf3cfaf41 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -263,6 +263,7 @@ struct VncState
     VncDisplay *vd;
     int need_update;
     int force_update;
+    int has_dirty;
     uint32_t features;
     int absolute;
     int last_x;