diff --git a/.github/workflows/pythonpackage.yml b/.github/workflows/pythonpackage.yml
index 4c67fbf..7f35b61 100644
--- a/.github/workflows/pythonpackage.yml
+++ b/.github/workflows/pythonpackage.yml
@@ -15,14 +15,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.5, 3.6, 3.7, 3.8]
+        python-version: [3.5, 3.6, 3.7, 3.8, 3.9]
 
     steps:
     - uses: actions/checkout@v2
       with:
         fetch-depth: 1000
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
diff --git a/gitdb/db/mem.py b/gitdb/db/mem.py
index 5b242e4..f588662 100644
--- a/gitdb/db/mem.py
+++ b/gitdb/db/mem.py
@@ -82,10 +82,7 @@ def size(self):
         return len(self._cache)
 
     def sha_iter(self):
-        try:
-            return self._cache.iterkeys()
-        except AttributeError:
-            return self._cache.keys()
+        return self._cache.keys()
 
     #{ Interface
     def stream_copy(self, sha_iter, odb):
diff --git a/gitdb/stream.py b/gitdb/stream.py
index b94ef24..d58d1a6 100644
--- a/gitdb/stream.py
+++ b/gitdb/stream.py
@@ -30,7 +30,6 @@
 from gitdb.utils.encoding import force_bytes
 
 has_perf_mod = False
-PY26 = sys.version_info[:2] < (2, 7)
 try:
     from gitdb_speedups._perf import apply_delta as c_apply_delta
     has_perf_mod = True
@@ -295,7 +294,7 @@ def read(self, size=-1):
         # However, the zlib VERSIONs as well as the platform check is used to further match the entries in the 
         # table in the github issue. This is it ... it was the only way I could make this work everywhere.
         # IT's CERTAINLY GOING TO BITE US IN THE FUTURE ... .
-        if PY26 or ((zlib.ZLIB_VERSION == '1.2.7' or zlib.ZLIB_VERSION == '1.2.5') and not sys.platform == 'darwin'):
+        if zlib.ZLIB_VERSION in ('1.2.7', '1.2.5') and not sys.platform == 'darwin':
             unused_datalen = len(self._zip.unconsumed_tail)
         else:
             unused_datalen = len(self._zip.unconsumed_tail) + len(self._zip.unused_data)
diff --git a/setup.py b/setup.py
index 59817d8..522a88f 100755
--- a/setup.py
+++ b/setup.py
@@ -38,6 +38,8 @@
         "Programming Language :: Python :: 3.4",
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7"
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
     ]
 )