diff --git a/.travis.yml b/.travis.yml
index 3ad8ad20..57508d53 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,7 +8,6 @@ install:
   - pip install cython
   - pip install --upgrade pip setuptools wheel
   - pip install -e .
-  - pip install progressbar
   - pip install pytest pytest-cov
   - pip install coveralls
 # command to run tests
diff --git a/docs/installation.rst b/docs/installation.rst
index 8271b01d..f3f7c79b 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -38,10 +38,15 @@ PySD calls on the core Python data analytics stack, and a third party parsing li
 * Numpy
 * Scipy
 * Pandas
-* Matplotlib
 * Parsimonious
+* xarray
+* xlrd
+* lxml
+* regex
+* chardet
 * black
 * openpyxl
+* progressbar
 
 These modules should build automatically if you are installing via `pip`. If you are building from
 the source code, or if pip fails to load them, they can be loaded with the same `pip` syntax as
@@ -50,9 +55,10 @@ above.
 
 Optional Dependencies
 ---------------------
-In order to be able to print the progress of a model integration process:
+In order to plot results from the model as shown in :doc:`basic usage <../basic_usage>`:
+
+* Matplotlib
 
-* progressbar
 
 These Python libraries bring additional data analytics capabilities to the analysis of SD models:
 
diff --git a/pysd/_version.py b/pysd/_version.py
index 5b601886..e4adfb83 100644
--- a/pysd/_version.py
+++ b/pysd/_version.py
@@ -1 +1 @@
-__version__ = "1.5.0"
+__version__ = "1.6.0"
diff --git a/pysd/py_backend/utils.py b/pysd/py_backend/utils.py
index 6cc1d967..455b74cf 100644
--- a/pysd/py_backend/utils.py
+++ b/pysd/py_backend/utils.py
@@ -7,6 +7,7 @@
 import warnings
 import keyword
 import regex as re
+import progressbar
 
 import xarray as xr
 
@@ -717,9 +718,6 @@ def __init__(self, maxval=None):
 
         self.counter = 0
 
-        # this way we made the package optional
-        import progressbar
-
         self.bar = progressbar.ProgressBar(
             maxval=self.maxval,
             widgets=[
diff --git a/requirements.txt b/requirements.txt
index 582d19ac..d2125109 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,12 +1,12 @@
 pandas
 parsimonious
 xarray
+xlrd
 lxml
-xlrd==1.2.0
-xlwt
 regex
 chardet
 black
 openpyxl
 scipy
+progressbar