diff --git a/pyqtgraph/SRTTransform3D.py b/pyqtgraph/SRTTransform3D.py
index 3c4edcc8..aedb200b 100644
--- a/pyqtgraph/SRTTransform3D.py
+++ b/pyqtgraph/SRTTransform3D.py
@@ -224,9 +224,9 @@ class SRTTransform3D(Transform3D):
             raise Exception("Argument 'nd' must be 2 or 3")
         
 if __name__ == '__main__':
-    import widgets
+    from . import widgets
     import GraphicsView
-    from functions import *
+    from .functions import *
     app = QtGui.QApplication([])
     win = QtGui.QMainWindow()
     win.show()
diff --git a/pyqtgraph/WidgetGroup.py b/pyqtgraph/WidgetGroup.py
index 2792aa98..4656cc62 100644
--- a/pyqtgraph/WidgetGroup.py
+++ b/pyqtgraph/WidgetGroup.py
@@ -23,7 +23,7 @@ def restoreSplitter(w, s):
     if type(s) is list:
         w.setSizes(s)
     elif type(s) is str:
-        w.restoreState(QtCore.QByteArray.fromPercentEncoding(s))
+        w.restoreState(QtCore.QByteArray.fromPercentEncoding(s.encode()))
     else:
         print("Can't configure QSplitter using object of type", type(s))
     if w.count() > 0:   ## make sure at least one item is not collapsed
diff --git a/pyqtgraph/configfile.py b/pyqtgraph/configfile.py
index 6ae8a0c5..fbedde4b 100644
--- a/pyqtgraph/configfile.py
+++ b/pyqtgraph/configfile.py
@@ -24,7 +24,7 @@ class ParseError(Exception):
     def __init__(self, message, lineNum, line, fileName=None):
         self.lineNum = lineNum
         self.line = line
-        #self.message = message
+        self.message = message
         self.fileName = fileName
         Exception.__init__(self, message)
         
diff --git a/pyqtgraph/functions.py b/pyqtgraph/functions.py
index 98cf301e..079cef25 100644
--- a/pyqtgraph/functions.py
+++ b/pyqtgraph/functions.py
@@ -16,7 +16,6 @@ from .python2_3 import asUnicode, basestring
 from .Qt import QtGui, QtCore, QT_LIB
 from . import getConfigOption, setConfigOptions
 from . import debug, reload
-from .reload import getPreviousVersion 
 from .metaarray import MetaArray
 
 
@@ -415,7 +414,7 @@ def makeArrowPath(headLen=20, headWidth=None, tipAngle=20, tailLen=20, tailWidth
     path.lineTo(0,0)
     return path
     
-    
+
 def eq(a, b):
     """The great missing equivalence function: Guaranteed evaluation to a single bool value.
     
diff --git a/pyqtgraph/graphicsItems/GradientEditorItem.py b/pyqtgraph/graphicsItems/GradientEditorItem.py
index 942b280b..39d9b610 100644
--- a/pyqtgraph/graphicsItems/GradientEditorItem.py
+++ b/pyqtgraph/graphicsItems/GradientEditorItem.py
@@ -33,7 +33,7 @@ def addGradientListToDocstring():
     """Decorator to add list of current pre-defined gradients to the end of a function docstring."""
     def dec(fn):
         if fn.__doc__ is not None:
-            fn.__doc__ = fn.__doc__ + str(Gradients.keys()).strip('[').strip(']')
+            fn.__doc__ = fn.__doc__ + str(list(Gradients.keys())).strip('[').strip(']')
         return fn
     return dec
 
diff --git a/pyqtgraph/graphicsItems/GraphicsItem.py b/pyqtgraph/graphicsItems/GraphicsItem.py
index 1a522446..9daf2a92 100644
--- a/pyqtgraph/graphicsItems/GraphicsItem.py
+++ b/pyqtgraph/graphicsItems/GraphicsItem.py
@@ -1,3 +1,4 @@
+from functools import reduce
 from ..Qt import QtGui, QtCore, isQObjectAlive
 from ..GraphicsScene import GraphicsScene
 from ..Point import Point
diff --git a/pyqtgraph/widgets/ColorMapWidget.py b/pyqtgraph/widgets/ColorMapWidget.py
index b5e25d94..74e468c0 100644
--- a/pyqtgraph/widgets/ColorMapWidget.py
+++ b/pyqtgraph/widgets/ColorMapWidget.py
@@ -79,7 +79,7 @@ class ColorMapParameter(ptree.types.GroupParameter):
         return item
         
     def fieldNames(self):
-        return self.fields.keys()
+        return list(self.fields.keys())
     
     def setFields(self, fields):
         """
diff --git a/pyqtgraph/widgets/TableWidget.py b/pyqtgraph/widgets/TableWidget.py
index 0378b5fc..c0e6ea90 100644
--- a/pyqtgraph/widgets/TableWidget.py
+++ b/pyqtgraph/widgets/TableWidget.py
@@ -64,7 +64,7 @@ class TableWidget(QtGui.QTableWidget):
         self.setSortingEnabled(kwds.pop('sortable'))
         
         if len(kwds) > 0:
-            raise TypeError("Invalid keyword arguments '%s'" % kwds.keys())
+            raise TypeError("Invalid keyword arguments '%s'" % list(kwds.keys()))
         
         self._sorting = None  # used when temporarily disabling sorting