diff --git a/.github/workflows/pythonapp.yml b/.github/workflows/pythonapp.yml
index 0b25712..334b523 100644
--- a/.github/workflows/pythonapp.yml
+++ b/.github/workflows/pythonapp.yml
@@ -8,21 +8,17 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: ['3.5', '3.6', '3.7', '3.8', '3.9', '3.10', 'pypy3']
+        python-version: ['3.7', '3.8', '3.9', '3.10', 'pypy3.9']
         os: [ubuntu-latest, windows-latest, macOS-latest]
         exclude:
           - os: macOS-latest
-            python-version: '3.5'
-          - os: macOS-latest
-            python-version: '3.6'
-          - os: macOS-latest
-            python-version: 'pypy3'
+            python-version: 'pypy3.9'
       fail-fast: false
     timeout-minutes: 3
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
         architecture: x64
@@ -35,7 +31,7 @@ jobs:
         PYTHONPATH: .
       run: |
         pip install pytest
-        pytest --flake8 --cov autoslot tests
+        pytest --cov autoslot tests
     - name: Extract branch name
       shell: bash
       run: echo "##[set-output name=branch;]$(echo ${GITHUB_REF#refs/heads/})"
diff --git a/autoslot.py b/autoslot.py
index c3cd935..fdcc8a4 100644
--- a/autoslot.py
+++ b/autoslot.py
@@ -31,7 +31,10 @@ def assignments_to_self(method) -> set:
     names = set()
     # a and b are a pair of bytecode instructions; b follows a.
     for a, b in zip(i0, i1):
-        accessing_self = (a.argval == instance_var and a.opname == 'LOAD_FAST')
+        accessing_self = (
+            a.argval == instance_var
+            and a.opname in ('LOAD_FAST', 'LOAD_DEREF')
+        )
         storing_attribute = (b.opname == 'STORE_ATTR')
         if accessing_self and storing_attribute:
             names.add(b.argval)
diff --git a/pyproject.toml b/pyproject.toml
index 4ee1b0b..0ed7c43 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,8 +11,6 @@ classifiers = [
     "License :: OSI Approved :: Apache Software License",
     "Natural Language :: English",
     "Programming Language :: Python",
-    "Programming Language :: Python :: 3.5",
-    "Programming Language :: Python :: 3.6",
     "Programming Language :: Python :: 3.7",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
diff --git a/requirements-test.txt b/requirements-test.txt
index 92b49d7..358911d 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,4 +1,3 @@
 pytest>=4.0.0
 pytest-cov
 coveralls
-pytest-flake8
diff --git a/tests/test_slots.py b/tests/test_slots.py
index 697a180..506fc58 100644
--- a/tests/test_slots.py
+++ b/tests/test_slots.py
@@ -47,6 +47,45 @@ def __init__(self, a, b):
         a.z = 3
 
 
+def test_slots_load_deref():
+    """Values can come from either LOAD_FAST or LOAD_DEREF
+    opcodes, so we need to handle both."""
+    class A(Slots):
+        def __init__(self, a, b):
+            self.x = a
+
+            def f():
+                """Simply by referring to self in another scope
+                is enough to change the `self` accessing opcodes
+                in __init__ to become LOAD_DEREF instead of
+                LOAD_FAST. We don't even have to call `f`."""
+                print(self)
+
+            self.y = b
+
+            # Testing to see that the
+            # bytecode processor identifies things
+            # correctly.
+            self.x = 'bleh'
+
+    assert '__module__' in A.__dict__
+    assert '__init__' in A.__dict__
+    assert '__slots__' in A.__dict__
+    assert A.__dict__['__slots__'] == {'x', 'y'}
+
+    a = A(1, 2)
+    assert hasattr(a, 'x')
+    assert hasattr(a, 'y')
+    # Just checking that we didn't pick up the wrong names
+    assert not hasattr(a, 'a')
+    assert not hasattr(a, 'b')
+    assert hasattr(a, '__slots__')
+    assert not hasattr(a, '__dict__')
+    # Can't assign new attributes
+    with pytest.raises(AttributeError):
+        a.z = 3
+
+
 def test_slots_weakref():
     """Basic usage of the Slots metaclass."""
     class A(Slots):