diff --git a/atrcopy/diskimages.py b/atrcopy/diskimages.py
index 6ba9828..fdae08d 100644
--- a/atrcopy/diskimages.py
+++ b/atrcopy/diskimages.py
@@ -292,7 +292,7 @@ class DiskImageBase(object):
 
     def get_file(self, dirent):
         segment = self.get_file_segment(dirent)
-        return segment.tostring()
+        return segment.tobytes()
 
     def get_file_segment(self, dirent):
         pass
diff --git a/atrcopy/dos33.py b/atrcopy/dos33.py
index a7713d0..add0c94 100644
--- a/atrcopy/dos33.py
+++ b/atrcopy/dos33.py
@@ -245,7 +245,7 @@ class Dos33Dirent(Dirent):
         self.sector = values[1]
         self._file_type = values[2] & 0x7f
         self.locked = values[2] & 0x80
-        self.filename = (bytes[3:0x20] - 0x80).tostring().rstrip()
+        self.filename = (bytes[3:0x20] - 0x80).tobytes().rstrip()
         self.num_sectors = int(values[4])
         self.is_sane = self.sanity_check(image)
 
@@ -699,12 +699,12 @@ class ProdosDiskImage(DiskImageBase):
         swap_order = False
         if (magic == [1, 56, 176, 3]).all():
             data, style = self.get_sectors(1)
-            prodos = data[3:9].tostring()
+            prodos = data[3:9].tobytes()
             if prodos == "PRODOS":
                 pass
             else:
                 data, style = self.get_sectors(14)
-                prodos = data[3:9].tostring()
+                prodos = data[3:9].tobytes()
                 if prodos == "PRODOS":
                     swap_order = True
                 else:
diff --git a/atrcopy/segments.py b/atrcopy/segments.py
index a3665a1..77f2587 100644
--- a/atrcopy/segments.py
+++ b/atrcopy/segments.py
@@ -71,7 +71,7 @@ class SegmentSaver(object):
 
     @classmethod
     def encode_data(cls, segment, ui_control):
-        return segment.tostring()
+        return segment.tobytes()
 
 
 class OrderWrapper(object):
@@ -119,8 +119,8 @@ class OrderWrapper(object):
     def unindexed(self):
         return self.np_data[self.order]
 
-    def tostring(self):
-        return self.np_data[self.order].tostring()
+    def tobytes(self):
+        return self.np_data[self.order].tobytes()
 
 
 class UserExtraData(object):
@@ -637,8 +637,8 @@ class DefaultSegment(object):
             raise IndexError("index %d not in this segment" % base_index)
         return int(index)
 
-    def tostring(self):
-        return self.data.tostring()
+    def tobytes(self):
+        return self.data.tobytes()
 
     def get_style_bits(self, **kwargs):
         return get_style_bits(**kwargs)
@@ -1053,7 +1053,7 @@ class DefaultSegment(object):
     @property
     def search_copy(self):
         if self._search_copy is None:
-            self._search_copy = self.data.tostring()
+            self._search_copy = self.data.tobytes()
         return self._search_copy
 
     def compare_segment(self, other_segment):