diff --git a/pinos/server/node.c b/pinos/server/node.c
index 07b3a2f82..810c9b082 100644
--- a/pinos/server/node.c
+++ b/pinos/server/node.c
@@ -258,6 +258,7 @@ do_pull (PinosNode *this)
 {
   SpaResult res = SPA_RESULT_OK;
   PinosPort *inport;
+  bool have_output = false;
 
   spa_list_for_each (inport, &this->input_ports, link) {
     PinosLink *link;
@@ -288,22 +289,22 @@ do_pull (PinosNode *this)
 
       if (res == SPA_RESULT_NEED_INPUT) {
         res = do_pull (outport->node);
-
-        *pi = *po;
         pinos_log_trace ("node %p: pull return %d", outport->node, res);
       }
-      else if (res == SPA_RESULT_HAVE_OUTPUT) {
-        *pi = *po;
-      }
-      else
+      else if (res < 0 && res != SPA_RESULT_HAVE_OUTPUT) {
         pinos_log_warn ("node %p: got process output %d", outport->node, res);
+      }
+
+      if (res == SPA_RESULT_HAVE_OUTPUT) {
+        *pi = *po;
+        pinos_log_trace ("node %p: have output %d %d", this, pi->status, pi->buffer_id);
+        have_output = true;
+      }
     }
-    if (pi->buffer_id != SPA_ID_INVALID) {
-      pinos_log_trace ("node %p: process input %d %d", this, pi->status, pi->buffer_id);
-      res =  spa_node_process_input (this->node);
-      if (res == SPA_RESULT_HAVE_OUTPUT)
-        break;
-    }
+  }
+  if (have_output) {
+    pinos_log_trace ("node %p: doing process input", this);
+    res =  spa_node_process_input (this->node);
   }
   return res;
 }
diff --git a/spa/plugins/audiomixer/audiomixer.c b/spa/plugins/audiomixer/audiomixer.c
index 9be4ecd9e..46f16b49a 100644
--- a/spa/plugins/audiomixer/audiomixer.c
+++ b/spa/plugins/audiomixer/audiomixer.c
@@ -733,7 +733,7 @@ spa_audiomixer_node_process_input (SpaNode *node)
       spa_log_trace (this->log, "audiomixer %p: queue buffer %d on port %d %zd %zd",
           this, b->outbuf->id, i, port->queued_bytes, min_queued);
     }
-    if (min_queued == SIZE_MAX || port->queued_bytes < min_queued)
+    if (port->queued_bytes > 0 && port->queued_bytes < min_queued)
       min_queued = port->queued_bytes;
   }
 
@@ -772,7 +772,7 @@ spa_audiomixer_node_process_output (SpaNode *node)
   res = SPA_RESULT_NEED_INPUT;
   /* produce more output if possible */
   if (this->state == STATE_OUT) {
-    size_t min_queued = -1;
+    size_t min_queued = SIZE_MAX;
 
     for (i = 0; i < MAX_PORTS; i++) {
       SpaAudioMixerPort *port = &this->in_ports[i];
@@ -780,10 +780,10 @@ spa_audiomixer_node_process_output (SpaNode *node)
       if (port->io == NULL || port->n_buffers == 0)
         continue;
 
-      if (min_queued == -1 || port->queued_bytes < min_queued)
+      if (port->queued_bytes > 0 && port->queued_bytes < min_queued)
         min_queued = port->queued_bytes;
     }
-    if (min_queued != -1 && min_queued > 0) {
+    if (min_queued != SIZE_MAX && min_queued > 0) {
       res = mix_output (this, min_queued);
     } else {
       this->state = STATE_IN;
diff --git a/spa/tests/test-mixer.c b/spa/tests/test-mixer.c
index 745ffd754..05ae44ce2 100644
--- a/spa/tests/test-mixer.c
+++ b/spa/tests/test-mixer.c
@@ -311,7 +311,7 @@ make_nodes (AppData *data)
 
   spa_pod_builder_init (&b, buffer, sizeof (buffer));
   spa_pod_builder_props (&b, &f[0], data->type.props,
-      SPA_POD_PROP (&f[1], data->type.props_device, 0, SPA_POD_TYPE_STRING, 1, "hw:0"),
+      SPA_POD_PROP (&f[1], data->type.props_device, 0, SPA_POD_TYPE_STRING, 1, "hw:1"),
       SPA_POD_PROP (&f[1], data->type.props_min_latency, 0, SPA_POD_TYPE_INT, 1, 256),
       SPA_POD_PROP (&f[1], data->type.props_live, 0, SPA_POD_TYPE_BOOL, 1, false));
   props = SPA_POD_BUILDER_DEREF (&b, f[0].ref, SpaProps);