--- a/media/libcubeb/src/cubeb_audiounit.cpp
+++ b/media/libcubeb/src/cubeb_audiounit.cpp
@@ -438,17 +438,18 @@ audiounit_init(cubeb ** context, char co
   *context = NULL;
 
   ctx = new cubeb;
   assert(ctx);
   PodZero(ctx, 1);
 
   ctx->ops = &audiounit_ops;
 
-  ctx->mutex = owned_critical_section();
+  // Call ctor directly because a mutex cannot be copied.
+  ctx->mutex.owned_critical_section::owned_critical_section();
 
   ctx->active_streams = 0;
 
   ctx->limit_streams = kCFCoreFoundationVersionNumber < kCFCoreFoundationVersionNumber10_7;
 #if !TARGET_OS_IPHONE
   cubeb_set_coreaudio_notification_runloop();
 #endif
 
@@ -1139,17 +1140,18 @@ audiounit_stream_init(cubeb * context,
    * full-duplex stream and different devices for input vs output. */
   stm->input_unit  = (input_stream_params != NULL) ? input_unit : NULL;
   stm->output_unit = (output_stream_params != NULL) ? output_unit : NULL;
   stm->context = context;
   stm->data_callback = data_callback;
   stm->state_callback = state_callback;
   stm->user_ptr = user_ptr;
   stm->device_changed_callback = NULL;
-  stm->mutex = owned_critical_section();
+  // Call ctor directly because a mutex cannot be copied.
+  stm->mutex.owned_critical_section::owned_critical_section();
 
   /* Init data members where necessary */
   stm->hw_latency_frames = UINT64_MAX;
 
   /* Silently clamp the latency down to the platform default, because we
    * synthetize the clock from the callbacks, and we want the clock to update
    * often. */
   latency_frames = audiounit_clamp_latency(stm, latency_frames);

--- a/media/libcubeb/src/cubeb_utils_unix.h
+++ b/media/libcubeb/src/cubeb_utils_unix.h
@@ -75,11 +75,15 @@ public:
 #ifdef DEBUG
     int r = pthread_mutex_lock(&mutex);
     assert(r == EDEADLK);
 #endif
   }
 
 private:
   pthread_mutex_t mutex;
+
+  // Disallow copy and assignment because pthread_mutex_t cannot be copied.
+  owned_critical_section(const owned_critical_section&);
+  owned_critical_section& operator=(const owned_critical_section&);
 };
 
 #endif /* CUBEB_UTILS_UNIX */

--- a/media/libcubeb/src/cubeb_utils_win.h
+++ b/media/libcubeb/src/cubeb_utils_win.h
@@ -57,11 +57,15 @@ public:
 #endif
   }
 
 private:
   CRITICAL_SECTION critical_section;
 #ifdef DEBUG
   DWORD owner;
 #endif
+
+  // Disallow copy and assignment because CRICICAL_SECTION cannot be copied.
+  owned_critical_section(const owned_critical_section&);
+  owned_critical_section& operator=(const owned_critical_section&);
 };
 
 #endif /* CUBEB_UTILS_WIN */

--- a/media/libcubeb/src/cubeb_wasapi.cpp
+++ b/media/libcubeb/src/cubeb_wasapi.cpp
@@ -1637,17 +1637,18 @@ wasapi_stream_init(cubeb * context, cube
   if (output_stream_params) {
     stm->output_stream_params = *output_stream_params;
     stm->output_device = output_device;
   }
 
   stm->latency = latency_frames;
   stm->volume = 1.0;
 
-  stm->stream_reset_lock = owned_critical_section();
+  // Call ctor directly because a critical section cannot be copied.
+  stm->stream_reset_lock.owned_critical_section::owned_critical_section();
 
   stm->reconfigure_event = CreateEvent(NULL, 0, 0, NULL);
   if (!stm->reconfigure_event) {
     LOG("Can't create the reconfigure event, error: %x\n", GetLastError());
     wasapi_stream_destroy(stm);
     return CUBEB_ERROR;
   }