diff --git a/python_modules/codegen.py b/python_modules/codegen.py
index affe5bc..0a13fdd 100644
--- a/python_modules/codegen.py
+++ b/python_modules/codegen.py
@@ -128,13 +128,13 @@ class CodeWriter:
             return
 
         if self.at_line_start:
-            self.out.write(u" " * self.indentation)
+            self.out.write(" " * self.indentation)
             self.at_line_start = False
         self.out.write(s)
         return self
 
     def newline(self):
-        self.out.write(u"\n")
+        self.out.write("\n")
         self.at_line_start = True
         return self
 
diff --git a/python_modules/ptypes.py b/python_modules/ptypes.py
index d68dc67..05234d8 100644
--- a/python_modules/ptypes.py
+++ b/python_modules/ptypes.py
@@ -111,7 +111,7 @@ def fix_attributes(attribute_list, valid_attributes=valid_attributes_generic):
         attrs[name] = lst
 
     # only one output attribute can be set
-    if len(output_attributes.intersection(attrs.keys())) > 1:
+    if len(output_attributes.intersection(list(attrs.keys()))) > 1:
         raise Exception("Multiple output type attributes specified %s" % output_attrs)
 
     return attrs
@@ -508,7 +508,7 @@ class ArrayType(Type):
         # a constant length array in the C structure is used) or a pointer
         # (in this case the pointer allocate the array).
         if (not self.is_constant_length()
-            and len(output_attributes.intersection(member.attributes.keys())) == 0
+            and len(output_attributes.intersection(list(member.attributes.keys()))) == 0
             and not member.member_type.is_pointer()):
             raise Exception("Array length must be a constant or some output specifiers must be set")
         # These attribute corresponds to specific structure size
@@ -1005,7 +1005,7 @@ class MessageType(ContainerType):
         if self.name == None:
             cms = list(self.reverse_members.keys())
             if len(cms) != 1:
-                raise "Unknown typename for message"
+                raise Exception("Unknown typename for message")
             cm = cms[0]
             channelname = cm.channel.member_name
             if channelname == None:
@@ -1025,7 +1025,7 @@ class MessageType(ContainerType):
         if self.name == None:
             cms = list(self.reverse_members.keys())
             if len(cms) != 1:
-                raise "Unknown typename for message"
+                raise Exception("Unknown typename for message")
             cm = cms[0]
             channelname = cm.channel.member_name
             if channelname == None:
diff --git a/spice_codegen.py b/spice_codegen.py
index 6d8d97a..579ba84 100755
--- a/spice_codegen.py
+++ b/spice_codegen.py
@@ -277,7 +277,7 @@ current:
     except:
         print('type %s' % t, file=sys.stderr)
         print(writer.getvalue(), file=sys.stderr)
-        traceback.print_exc(sys.stderr)
+        traceback.print_exc(file=sys.stderr)
         sys.exit(1)
 
 def generate_declarations():