diff --git a/demo/realtime_plot.py b/demo/realtime_plot.py
index 229309b..ec5f3d0 100755
--- a/demo/realtime_plot.py
+++ b/demo/realtime_plot.py
@@ -21,7 +21,7 @@ def data_gen():
     #endless loop which gets data
     while True:
         data = np.zeros(0)
-        while (not c.hasSampleAvilabale() == 0):
+        while c.hasSampleAvilabale():
             sample = c.getSampleFromBuffer()
             data = np.append(data,sample[0])
         yield data
diff --git a/pyusbdux.cpp b/pyusbdux.cpp
index fb5fb85..1fac2e3 100644
--- a/pyusbdux.cpp
+++ b/pyusbdux.cpp
@@ -168,7 +168,9 @@ sample_p getSampleFromBuffer() {
 
 int hasSampleAvilabale() {
 	if (dev == NULL) throw "Device not open";
-	return comedi_get_buffer_contents(dev,subdevice) > 0;
+	int ret = comedi_get_buffer_contents(dev,subdevice);
+	if (ret < 0) throw "Device error. Possible disconnect.";
+	return ret > 0;
 }
 
 
diff --git a/setup.py b/setup.py
index 0e769e5..5be1dc6 100755
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/python3
 
 """
 setup.py file for pyusbdux.py
@@ -21,7 +21,7 @@ def read(fname):
 
 						   
 setup (name = 'pyusbdux',
-       version = '1.3.3',
+       version = '1.3.4',
        author      = "Bernd Porr",
        author_email = "mail@berndporr.me.uk",
        url = "https://github.com/berndporr/pyusbdux",