diff --git a/tests/duplex.cpp b/tests/duplex.cpp
index 291d2aa..06462f2 100644
--- a/tests/duplex.cpp
+++ b/tests/duplex.cpp
@@ -97,6 +97,11 @@ int main( int argc, char *argv[] )
   oParams.nChannels = channels;
   oParams.firstChannel = oOffset;
 
+  if ( iDevice == 0 )
+    iParams.deviceId = adac.getDefaultInputDevice();
+  if ( oDevice == 0 )
+    oParams.deviceId = adac.getDefaultOutputDevice();
+
   RtAudio::StreamOptions options;
   //options.flags |= RTAUDIO_NONINTERLEAVED;
 
diff --git a/tests/playraw.cpp b/tests/playraw.cpp
index 75e7d13..f11f83c 100644
--- a/tests/playraw.cpp
+++ b/tests/playraw.cpp
@@ -125,6 +125,9 @@ int main( int argc, char *argv[] )
   oParams.nChannels = channels;
   oParams.firstChannel = offset;
 
+  if ( device == 0 )
+    oParams.deviceId = dac.getDefaultOutputDevice();
+
   data.channels = channels;
   try {
     dac.openStream( &oParams, NULL, FORMAT, fs, &bufferFrames, &output, (void *)&data );
diff --git a/tests/playsaw.cpp b/tests/playsaw.cpp
index 2be179b..d1953b6 100644
--- a/tests/playsaw.cpp
+++ b/tests/playsaw.cpp
@@ -174,6 +174,9 @@ int main( int argc, char *argv[] )
   oParams.nChannels = channels;
   oParams.firstChannel = offset;
 
+  if ( device == 0 )
+    oParams.deviceId = dac.getDefaultOutputDevice();
+
   options.flags = RTAUDIO_HOG_DEVICE;
   options.flags |= RTAUDIO_SCHEDULE_REALTIME;
 #if !defined( USE_INTERLEAVED )
diff --git a/tests/testall.cpp b/tests/testall.cpp
index ec7107b..419f27b 100644
--- a/tests/testall.cpp
+++ b/tests/testall.cpp
@@ -128,6 +128,9 @@ int main( int argc, char *argv[] )
   oParams.nChannels = channels;
   oParams.firstChannel = oOffset;
 
+  if ( oDevice == 0 )
+    oParams.deviceId = dac.getDefaultOutputDevice();
+
   RtAudio::StreamOptions options;
   options.flags = RTAUDIO_HOG_DEVICE;
   try {
@@ -192,6 +195,8 @@ int main( int argc, char *argv[] )
   iParams.deviceId = iDevice;
   iParams.nChannels = channels;
   iParams.firstChannel = iOffset;
+  if ( iDevice == 0 )
+    iParams.deviceId = dac.getDefaultInputDevice();
   options.flags = RTAUDIO_NONINTERLEAVED;
   try {
     dac.openStream( &oParams, &iParams, RTAUDIO_SINT32, fs, &bufferFrames, &inout, (void *)&bufferBytes, &options );
diff --git a/tests/teststops.cpp b/tests/teststops.cpp
index 5c6ed38..e24c064 100644
--- a/tests/teststops.cpp
+++ b/tests/teststops.cpp
@@ -121,6 +121,11 @@ int main( int argc, char *argv[] )
   iParams.nChannels = mydata.channels;
   iParams.firstChannel = iOffset;
 
+  if ( iDevice == 0 )
+    iParams.deviceId = adc->getDefaultInputDevice();
+  if ( oDevice == 0 )
+    oParams.deviceId = adc->getDefaultOutputDevice();
+
   // First, test external stopStream() calls.
   mydata.pulseCount = PULSE_RATE * fs;
   mydata.nFrames = 50 * fs;