diff --git a/examples/beep.rs b/examples/beep.rs
index 6312d25..0a80a80 100644
--- a/examples/beep.rs
+++ b/examples/beep.rs
@@ -4,9 +4,9 @@ extern crate cpal;
 use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
 
 fn main() -> Result<(), anyhow::Error> {
-    //let host = cpal::default_host();
-    let host =
-        cpal::host_from_id(cpal::platform::HostId::Asio).expect("failed to initialise ASIO host");
+    let host = cpal::default_host();
+    //let host =
+    //    cpal::host_from_id(cpal::platform::HostId::Asio).expect("failed to initialise ASIO host");
     let device = host
         .default_output_device()
         .expect("failed to find a default output device");
@@ -26,7 +26,7 @@ where
     T: cpal::Sample,
 {
     let mut config: cpal::StreamConfig = config.clone();
-    config.buffer_size = cpal::BufferSize::Fixed(256);
+    config.buffer_size = cpal::BufferSize::Fixed(16);
 
     let sample_rate = config.sample_rate.0 as f32;
     let channels = config.channels as usize;
@@ -43,6 +43,7 @@ where
     let stream = device.build_output_stream(
         &config,
         move |data: &mut [T], _: &cpal::OutputCallbackInfo| {
+            println!("data len = {}", data.len());
             write_data(data, channels, &mut next_value)
         },
         err_fn,
diff --git a/src/host/coreaudio/mod.rs b/src/host/coreaudio/mod.rs
index 5010901..bb1f8ed 100644
--- a/src/host/coreaudio/mod.rs
+++ b/src/host/coreaudio/mod.rs
@@ -278,11 +278,8 @@ impl Device {
             let ranges: *mut AudioValueRange = ranges.as_mut_ptr() as *mut _;
             let ranges: &'static [AudioValueRange] = slice::from_raw_parts(ranges, n_ranges);
 
-            let mut audio_unit = audio_unit_from_device(self, true)?;
-            let buffer_size = match get_io_buffer_frame_size_range(&audio_unit) {
-                Ok(v) => v.unwrap(),
-                Err(_) => return SupportedStreamConfigsError::DeviceNotAvailable,
-            };
+            let audio_unit = audio_unit_from_device(self, true)?;
+            let buffer_size = get_io_buffer_frame_size_range(&audio_unit)?;
 
             // Collect the supported formats for the device.
             let mut fmts = vec![];
@@ -291,7 +288,7 @@ impl Device {
                     channels: n_channels as ChannelCount,
                     min_sample_rate: SampleRate(range.mMinimum as _),
                     max_sample_rate: SampleRate(range.mMaximum as _),
-                    buffer_size,
+                    buffer_size: buffer_size.clone(),
                     sample_format: sample_format,
                 };
                 fmts.push(fmt);
@@ -439,6 +436,24 @@ impl From<coreaudio::Error> for BuildStreamError {
     }
 }
 
+impl From<coreaudio::Error> for SupportedStreamConfigsError {
+    fn from(err: coreaudio::Error) -> SupportedStreamConfigsError {
+        let description = format!("{}", err);
+        let err = BackendSpecificError { description };
+        // Check for possible DeviceNotAvailable variant
+        SupportedStreamConfigsError::BackendSpecific { err }
+    }
+}
+
+impl From<coreaudio::Error> for DefaultStreamConfigError {
+    fn from(err: coreaudio::Error) -> DefaultStreamConfigError {
+        let description = format!("{}", err);
+        let err = BackendSpecificError { description };
+        // Check for possible DeviceNotAvailable variant
+        DefaultStreamConfigError::BackendSpecific { err }
+    }
+}
+
 // Create a coreaudio AudioStreamBasicDescription from a CPAL Format.
 fn asbd_from_config(
     config: &StreamConfig,
@@ -671,12 +686,19 @@ impl Device {
 
         // Set the buffersize
         match config.buffer_size {
-            BufferSize::Fixed(v) => audio_unit.set_property(
-                kAudioDevicePropertyBufferFrameSize,
-                scope,
-                element,
-                Some(&v),
-            )?,
+            BufferSize::Fixed(v) => {
+                let buffer_size_range = get_io_buffer_frame_size_range(&audio_unit)?;
+                if v >= buffer_size_range.min && v <= buffer_size_range.max {
+                    audio_unit.set_property(
+                        kAudioDevicePropertyBufferFrameSize,
+                        scope,
+                        element,
+                        Some(&v),
+                    )?
+                } else {
+                    return Err(BuildStreamError::StreamConfigNotSupported);
+                }
+            }
             BufferSize::Default => (),
         }
 
@@ -753,12 +775,19 @@ impl Device {
 
         // Set the buffersize
         match config.buffer_size {
-            BufferSize::Fixed(v) => audio_unit.set_property(
-                kAudioDevicePropertyBufferFrameSize,
-                scope,
-                element,
-                Some(&v),
-            )?,
+            BufferSize::Fixed(v) => {
+                let buffer_size_range = get_io_buffer_frame_size_range(&audio_unit)?;
+                if v >= buffer_size_range.min && v <= buffer_size_range.max {
+                    audio_unit.set_property(
+                        kAudioDevicePropertyBufferFrameSize,
+                        scope,
+                        element,
+                        Some(&v),
+                    )?
+                } else {
+                    return Err(BuildStreamError::StreamConfigNotSupported);
+                }
+            }
             BufferSize::Default => (),
         }