diff --git a/.travis.yml b/.travis.yml
index c46d0d1d6..eab55af63 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,8 +11,6 @@ script:
   - scripts/validate_filenames.py  # no uppercase and no spaces
   - mypy --ignore-missing-imports .
   - pytest . --doctest-modules
-      --ignore=data_structures/stacks/balanced_parentheses.py
-      --ignore=data_structures/stacks/infix_to_postfix_conversion.py
       --ignore=file_transfer_protocol/ftp_send_receive.py
       --ignore=file_transfer_protocol/ftp_client_server.py
       --ignore=machine_learning/linear_regression.py
diff --git a/data_structures/stacks/balanced_parentheses.py b/data_structures/stacks/balanced_parentheses.py
index 3229d19c8..36a4e07a9 100644
--- a/data_structures/stacks/balanced_parentheses.py
+++ b/data_structures/stacks/balanced_parentheses.py
@@ -1,6 +1,7 @@
 from __future__ import print_function
 from __future__ import absolute_import
-from stack import Stack
+
+from .stack import Stack
 
 __author__ = 'Omkar Pathak'
 
diff --git a/data_structures/stacks/infix_to_postfix_conversion.py b/data_structures/stacks/infix_to_postfix_conversion.py
index e71dccf1f..9376b55b8 100644
--- a/data_structures/stacks/infix_to_postfix_conversion.py
+++ b/data_structures/stacks/infix_to_postfix_conversion.py
@@ -2,7 +2,7 @@ from __future__ import print_function
 from __future__ import absolute_import
 import string
 
-from stack import Stack
+from .stack import Stack
 
 __author__ = 'Omkar Pathak'