diff --git a/PlotItem.py b/PlotItem.py
index 0cbc9459..eb786f29 100644
--- a/PlotItem.py
+++ b/PlotItem.py
@@ -998,7 +998,7 @@ class PlotItem(QtGui.QGraphicsWidget):
         if arr.ndim != 1:
             raise Exception("Array must be 1D to plot (shape is %s)" % arr.shape)
         if x is None:
-            x = arange(arr.shape[0])
+            x = np.arange(arr.shape[0])
         if x.ndim != 1:
             raise Exception("X array must be 1D to plot (shape is %s)" % x.shape)
         c = PlotCurveItem(arr, x=x)
diff --git a/examples/test_PlotWidget.py b/examples/test_PlotWidget.py
index 80e4a9c4..a5f4960e 100755
--- a/examples/test_PlotWidget.py
+++ b/examples/test_PlotWidget.py
@@ -5,6 +5,7 @@ import sys, os
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..'))
 
 from scipy import random
+from numpy import array, arange
 from PyQt4 import QtGui, QtCore
 from pyqtgraph.PlotWidget import *
 from pyqtgraph.graphicsItems import *
@@ -90,4 +91,4 @@ for i in range(0, 5):
         yd, xd = rand(10000)
         pw2.plot(yd*(j+1), xd, params={'iter': i, 'val': j})
     
-#app.exec_()
+app.exec_()
diff --git a/graphicsItems.py b/graphicsItems.py
index 299b9cf8..de935afa 100644
--- a/graphicsItems.py
+++ b/graphicsItems.py
@@ -573,7 +573,7 @@ class PlotCurveItem(GraphicsObject):
             self.xData = x
         
         if x is None:
-            self.xData = arange(0, self.yData.shape[0])
+            self.xData = np.arange(0, self.yData.shape[0])
 
         if self.xData.shape != self.yData.shape:
             raise Exception("X and Y arrays must be the same shape--got %s and %s." % (str(x.shape), str(y.shape)))