diff --git a/dev-requirements.txt b/dev-requirements.txt
index 039b7435b..eafb45609 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -1,6 +1,7 @@
 coveralls
 flake8
 nose
+pymongo>=3.3,<4.0
 twine
 twython
 sphinx>=1.8,<1.9
diff --git a/docs/storage/index.rst b/docs/storage/index.rst
index 69d334d28..05786d385 100644
--- a/docs/storage/index.rst
+++ b/docs/storage/index.rst
@@ -41,6 +41,13 @@ SQL Storage Adapter
 MongoDB Storage Adapter
 =======================
 
+.. note::
+
+   Before you can use this storage adapter you will need to install
+   `pymongo`_. Consider adding ``pymongo`` to your project's
+   ``requirements.txt`` file so you can keep track of your dependencies
+   and their versions.
+
 .. autoclass:: chatterbot.storage.MongoDatabaseAdapter
    :members:
 
@@ -64,3 +71,4 @@ each of the databases that ChatterBot comes with support for.
 * MongoDB: No migrations are provided.
 
 .. _Alembic: https://alembic.sqlalchemy.org
+.. _pymongo: https://pypi.org/project/pymongo/
diff --git a/requirements.txt b/requirements.txt
index 00c85a6c6..4a000abd0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,6 @@ git+git://github.com/gunthercox/chatterbot-corpus@master#egg=chatterbot_corpus
 mathparse>=0.1,<0.2
 nltk>=3.2,<4.0
 pint>=0.8.1
-pymongo>=3.3,<4.0
 python-dateutil>=2.7,<2.8
 pyyaml>=5.1,<5.2
 spacy>=2.1,<2.2