diff --git a/media/libcubeb/moz.yaml b/media/libcubeb/moz.yaml
index c90f95e09a0a..c2eea799d1bf 100644
--- a/media/libcubeb/moz.yaml
+++ b/media/libcubeb/moz.yaml
@@ -19,5 +19,5 @@ origin:
   license: "ISC"
 
   # update.sh will update this value
-  release: "85f1cf48dffd749dd32798681955155e1a1a6ff5 (2020-12-07 08:11:33 +0000)"
+  release: "4a83932caee16c9ee404b39144620fcbcc7a842f (2021-01-19 16:05:14 +0100)"
 
diff --git a/media/libcubeb/src/cubeb_oss.c b/media/libcubeb/src/cubeb_oss.c
index 32a4bf6de482..8c44c9e8d08a 100644
--- a/media/libcubeb/src/cubeb_oss.c
+++ b/media/libcubeb/src/cubeb_oss.c
@@ -781,6 +781,28 @@ oss_put_play_frames(cubeb_stream * s, unsigned int nframes)
   return 0;
 }
 
+static int
+oss_wait_playfd_for_space(cubeb_stream * s)
+{
+  /* For non-duplex stream we have to wait until we have space in the
+   * buffer */
+  int rate = s->play.info.sample_rate;
+  struct pollfd pfd;
+
+  pfd.events = POLLOUT|POLLHUP;
+  pfd.revents = 0;
+  pfd.fd = s->play.fd;
+
+  if (poll(&pfd, 1, s->nfr * 1000 + rate - 1 / rate) == -1) {
+    return CUBEB_ERROR;
+  }
+
+  if (pfd.revents & POLLHUP) {
+    return CUBEB_ERROR;
+  }
+  return 0;
+}
+
 /* 1 - Stopped by cubeb_stream_stop, otherwise 0 */
 static int
 oss_audio_loop(cubeb_stream * s, cubeb_state *new_state)
@@ -873,26 +895,31 @@ oss_audio_loop(cubeb_stream * s, cubeb_state *new_state)
       goto breakdown;
     }
 
-    audio_buf_info bi;
     if (play_on) {
-      if (ioctl(s->play.fd, SNDCTL_DSP_GETOSPACE, &bi)) {
-        state = CUBEB_STATE_ERROR;
-        goto breakdown;
-      }
       /*
        * In duplex mode, playback direction drives recording direction to
        * prevent building up latencies.
        */
+
+      if (oss_wait_playfd_for_space(s) != 0) {
+        state = CUBEB_STATE_ERROR;
+        goto breakdown;
+      }
+
+      audio_buf_info bi;
+      if (ioctl(s->play.fd, SNDCTL_DSP_GETOSPACE, &bi)) {
+        state = CUBEB_STATE_ERROR;
+        goto breakdown;
+      }
       nfr = bi.fragsize * bi.fragments / s->play.frame_size;
       if (nfr > s->bufframes) {
         nfr = s->bufframes;
       }
+    } else {
+      nfr = s->nfr;
     }
 
     if (record_on) {
-      if (nfr == 0) {
-        nfr = s->nfr;
-      }
       if (oss_get_rec_frames(s, nfr) == CUBEB_ERROR) {
         state = CUBEB_STATE_ERROR;
         goto breakdown;
diff --git a/media/libcubeb/src/cubeb_wasapi.cpp b/media/libcubeb/src/cubeb_wasapi.cpp
index 30a6d06c7e20..b7b337ce7829 100644
--- a/media/libcubeb/src/cubeb_wasapi.cpp
+++ b/media/libcubeb/src/cubeb_wasapi.cpp
@@ -778,12 +778,6 @@ hns_to_frames(cubeb_stream * stm, REFERENCE_TIME hns)
   return hns_to_frames(get_rate(stm), hns);
 }
 
-REFERENCE_TIME
-frames_to_hns(cubeb_stream * stm, uint32_t frames)
-{
-  return std::ceil(frames * 10000000.0 / get_rate(stm));
-}
-
 REFERENCE_TIME
 frames_to_hns(uint32_t rate, uint32_t frames)
 {
@@ -1834,7 +1828,8 @@ initialize_iaudioclient2(com_ptr<IAudioClient> & audio_client)
   return CUBEB_OK;
 }
 
-static bool
+// Not static to suppress a warning.
+/* static */ bool
 initialize_iaudioclient3(com_ptr<IAudioClient> & audio_client,
                          cubeb_stream * stm,
                          const com_heap_ptr<WAVEFORMATEX> & mix_format,
@@ -2185,7 +2180,7 @@ int setup_wasapi_stream_one_side(cubeb_stream * stm,
 
 void wasapi_find_matching_output_device(cubeb_stream * stm) {
   HRESULT hr;
-  cubeb_device_info * input_device;
+  cubeb_device_info * input_device = nullptr;
   cubeb_device_collection collection;
 
   // Only try to match to an output device if the input device is a bluetooth
@@ -2207,6 +2202,9 @@ void wasapi_find_matching_output_device(cubeb_stream * stm) {
   }
 
   int rv = wasapi_enumerate_devices(stm->context, (cubeb_device_type)(CUBEB_DEVICE_TYPE_INPUT|CUBEB_DEVICE_TYPE_OUTPUT), &collection);
+  if (rv != CUBEB_OK) {
+    return;
+  }
 
   // Find the input device, and then find the output device with the same group
   // id and the same rate.
@@ -2220,11 +2218,13 @@ void wasapi_find_matching_output_device(cubeb_stream * stm) {
 
   for (uint32_t i = 0; i < collection.count; i++) {
     cubeb_device_info dev = collection.device[i];
-    if (dev.type == CUBEB_DEVICE_TYPE_OUTPUT &&
-        dev.group_id && !strcmp(dev.group_id, input_device->group_id) &&
+    if (dev.type == CUBEB_DEVICE_TYPE_OUTPUT && dev.group_id && input_device &&
+        !strcmp(dev.group_id, input_device->group_id) &&
         dev.default_rate == input_device->default_rate) {
-      LOG("Found matching device for %s: %s", input_device->friendly_name, dev.friendly_name);
-      stm->output_device_id = utf8_to_wstr(reinterpret_cast<char const *>(dev.devid));
+      LOG("Found matching device for %s: %s", input_device->friendly_name,
+          dev.friendly_name);
+      stm->output_device_id =
+          utf8_to_wstr(reinterpret_cast<char const *>(dev.devid));
     }
   }