diff --git a/.travis.yml b/.travis.yml
index 3f55ece0..ac64a1bf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,7 +2,6 @@ language: python
 
 env:
   global:
-    - DEPS="scipy matplotlib numpy tqdm transforms3d diffpy.structure"
     - TEST_DEPS="pytest pytest-cov coveralls"
 
 matrix:
@@ -34,7 +33,7 @@ before_install:
   - df -h
 
 install:
-  - conda install -y $DEPS $TEST_DEPS;
+  - conda install -y $TEST_DEPS;
   - pip install .
 
 script:
diff --git a/appveyor.yml b/appveyor.yml
index 731855c7..b9ceb438 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -2,7 +2,6 @@
 environment:
 
   global:
-    DEPS: "scipy matplotlib numpy tqdm transforms3d diffpy.structure"
     TEST_DEPS: "pytest"
     MPLBACKEND: "agg"
 
@@ -26,7 +25,7 @@ install:
   - "conda activate testenv"
 
   # Install the dependencies of diffsims.
-  - 'conda install -yq %DEPS% %TEST_DEPS%'
+  - 'conda install -yq %TEST_DEPS%'
 
   # Install our package
   - 'pip install -e .'
diff --git a/setup.py b/setup.py
index 7bdfac3e..0569ba60 100644
--- a/setup.py
+++ b/setup.py
@@ -46,11 +46,15 @@
     packages=find_packages(),
     # adjust the tabbing
     install_requires=[
-        'scikit-image == 0.15.0',
-        'matplotlib < 3.1.0',
+        'scipy>=0.15',
+        'numpy>=1.10',
+        'scikit-image==0.15.0',
+        'matplotlib==3.0.3',
+        'tqdm>=0.4.9',
         'transforms3d',
-        'diffpy.structure >= 3.0.0'  # First Python 3 support
+        'diffpy.structure>=3.0.0'  # First Python 3 support
     ],
+    python_requires='>=3.6',
     package_data={
         "": ["LICENSE", "readme.rst", ],
         "diffsims": ["*.py"],