diff --git a/Exercises/ex2_5.md b/Exercises/ex2_5.md
index 47a7150..ae8072d 100644
--- a/Exercises/ex2_5.md
+++ b/Exercises/ex2_5.md
@@ -175,7 +175,7 @@ function.
 
 import collections
 ...
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         self.routes = []      # Columns
         self.dates = []
@@ -204,7 +204,7 @@ into 4 separate `append()` operations.
 # readrides.py
 ...
 
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         # Each value is a list with all of the values (a column)
         self.routes = []
diff --git a/Exercises/soln2_5.md b/Exercises/soln2_5.md
index eab490e..abe66db 100644
--- a/Exercises/soln2_5.md
+++ b/Exercises/soln2_5.md
@@ -93,7 +93,7 @@ def read_rides_as_columns(filename):
 # The great "fake"
 
 import collections
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         # Each value is a list with all of the values (a column)
         self.routes = []
diff --git a/Solutions/2_5/readrides.py b/Solutions/2_5/readrides.py
index 5c1f1bc..f060da6 100644
--- a/Solutions/2_5/readrides.py
+++ b/Solutions/2_5/readrides.py
@@ -88,7 +88,7 @@ def read_rides_as_columns(filename):
 # The great "fake"
 
 import collections
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         # Each value is a list with all of the values (a column)
         self.routes = []
diff --git a/Solutions/2_6/colreader.py b/Solutions/2_6/colreader.py
index 0b28af6..1d6f67a 100644
--- a/Solutions/2_6/colreader.py
+++ b/Solutions/2_6/colreader.py
@@ -3,7 +3,7 @@
 import collections
 import csv
 
-class DataCollection(collections.Sequence):
+class DataCollection(collections.abc.Sequence):
     def __init__(self, columns):
         self.column_names = list(columns)
         self.column_data = list(columns.values())
@@ -34,4 +34,3 @@ if __name__ == '__main__':
     tracemalloc.start()
     data = read_csv_as_columns('../../Data/ctabus.csv', [intern, intern, intern, int])
     print(tracemalloc.get_traced_memory())
-