diff --git a/CHANGELOG b/CHANGELOG
index 49fc7f204..b9bfb74de 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,7 @@ Unreleased: mitmproxy next
 
 ** Full Changelog **
 
+    * Support for Python 3.9 (@mhils)
     * Add MsgPack content viewer (@tasn)
     * Use `@charset` to decode CSS files if available (@prinzhorn)
     * Fix links to anticache docs in mitmweb and use HTTPS for links to documentation (@rugk)
diff --git a/mitmproxy/tools/main.py b/mitmproxy/tools/main.py
index cd99e6d5f..60c3e2e86 100644
--- a/mitmproxy/tools/main.py
+++ b/mitmproxy/tools/main.py
@@ -11,11 +11,11 @@ if sys.version_info < (3, 6):
     # This must be before any mitmproxy imports, as they already break!
     # Keep all other imports below with the 'noqa' magic comment.
     print("#" * 76, file=sys.stderr)
-    print("# mitmproxy requires Python 3.6 or higher!                                 #", file=sys.stderr)
+    print("# mitmproxy requires Python 3.6 or higher!                                  #", file=sys.stderr)
     print("#" + " " * 74 + "#", file=sys.stderr)
-    print("# Please upgrade your Python intepreter or use our mitmproxy binaries from #", file=sys.stderr)
-    print("# https://mitmproxy.org. If your operating system does not include the     #", file=sys.stderr)
-    print("# required Python version, you can try using pyenv or similar tools.       #", file=sys.stderr)
+    print("# Please upgrade your Python interpreter or use our mitmproxy binaries from #", file=sys.stderr)
+    print("# https://mitmproxy.org. If your operating system does not include the      #", file=sys.stderr)
+    print("# required Python version, you can try using pyenv or similar tools.        #", file=sys.stderr)
     print("#" * 76, file=sys.stderr)
     sys.exit(1)
 else:
diff --git a/setup.py b/setup.py
index ecf39d8e1..2e15eda46 100644
--- a/setup.py
+++ b/setup.py
@@ -69,8 +69,8 @@ setup(
         "click>=7.0,<8",
         "cryptography>=3.0,<3.1.1",
         "flask>=1.1.1,<1.2",
-        "h2>=3.2.0,<4",
-        "hyperframe>=5.1.0,<6",
+        "h2>=4.0,<5; python_version>='3.6.0'",  # python_version only needed to make "py36+ required" message work
+        "hyperframe>=6.0,<7; python_version>='3.6.0'",  # python_version only needed to make "py36+ required" message work
         "kaitaistruct>=0.7,<0.9",
         "ldap3>=2.8,<2.9",
         "msgpack>=1.0.0, <1.1.0",
@@ -98,15 +98,15 @@ setup(
         'dev': [
             "asynctest>=0.12.0",
             "Flask>=1.0,<1.2",
-            "hypothesis>=5.8,<5.30",
+            "hypothesis>=5.8,<6",
             "parver>=0.1,<2.0",
             "pytest-asyncio>=0.10.0,<0.14,!=0.14",
             "pytest-cov>=2.7.1,<3",
             "pytest-timeout>=1.3.3,<2",
-            "pytest-xdist>=1.29,<2.2",
-            "pytest>=5.1.3,<7",
+            "pytest-xdist>=2.1.0,<3",
+            "pytest>=6.1.0,<7",
             "requests>=2.9.1,<3",
-            "tox>=3.5,<3.20",
+            "tox>=3.5,<4",
         ]
     }
 )
diff --git a/tox.ini b/tox.ini
index fd3b09723..6df8dd72e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,7 +23,7 @@ commands =
   bash -c "mitmdump --version 2>&1 | grep 'mitmproxy requires Python 3.6'"
 
 [testenv:flake8]
-deps = flake8==3.8.3
+deps = flake8==3.8.4
 commands =
   flake8 --jobs 8 mitmproxy pathod examples test release