diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c73bc005..1f946e5f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -47,10 +47,6 @@ jobs:
             os: ubuntu-20.04
             python-version: 2.7
             tox-env: gmpy2py27
-          - name: py3.5
-            os: ubuntu-20.04
-            python-version: 3.5
-            tox-env: py35
           - name: py3.6
             os: ubuntu-20.04
             python-version: 3.6
@@ -268,7 +264,7 @@ jobs:
       - name: Install mutation testing dependencies
         if: ${{ matrix.mutation == 'true' }}
         run: |
-          pip install https://github.com/sixty-north/cosmic-ray/archive/master.zip
+          pip install cosmic-ray
           pip install pytest-timeout
       - name: Display installed python package versions
         run: pip list
@@ -419,7 +415,7 @@ jobs:
           key: sessions-${{ github.sha }}
       - name: Install cosmic-ray
         run: |
-          pip3 install https://github.com/sixty-north/cosmic-ray/archive/master.zip
+          pip3 install cosmic-ray
           pip install pytest-timeout
       - name: Install dependencies
         run: |
@@ -495,7 +491,7 @@ jobs:
       - name: Install build dependencies
         run: |
           pip install -r build-requirements.txt
-          pip install https://github.com/sixty-north/cosmic-ray/archive/master.zip
+          pip install cosmic-ray
           pip install pytest-timeout
       - name: Run mutation testing
         run: |
@@ -647,7 +643,7 @@ jobs:
           key: sessions-${{ github.sha }}-19-done
       - name: Install cosmic-ray
         run: |
-          pip3 install https://github.com/sixty-north/cosmic-ray/archive/master.zip
+          pip3 install cosmic-ray
           pip install pytest-timeout
       - name: Install dependencies
         run: |
diff --git a/README.md b/README.md
index 6c43f85d..980abc1e 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ curves over prime fields.
 ## Dependencies
 
 This library uses only Python and the 'six' package. It is compatible with
-Python 2.6, 2.7, and 3.5+. It also supports execution on alternative
+Python 2.6, 2.7, and 3.6+. It also supports execution on alternative
 implementations like pypy and pypy3.
 
 If `gmpy2` or `gmpy` is installed, they will be used for faster arithmetic.
diff --git a/setup.py b/setup.py
index a9ae2439..341fe734 100755
--- a/setup.py
+++ b/setup.py
@@ -27,14 +27,14 @@
     package_dir={"": "src"},
     license="MIT",
     cmdclass=commands,
-    python_requires=">=2.6, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*",
+    python_requires=">=2.6, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, "
+    "!=3.5.*",
     classifiers=[
         "Programming Language :: Python",
         "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 2.6",
         "Programming Language :: Python :: 2.7",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",