diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c3b1a23c..decb7a91 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.7, 3.8, 3.9]
 
     steps:
       - uses: actions/checkout@v2
diff --git a/README.md b/README.md
index dddfa6fa..5139f524 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ Everybody likes multiple dispatch, just like everybody likes plums.
 
 ## Installation
 
-Plum requires Python 3.6 or higher.
+Plum requires Python 3.7 or higher.
 
 ```bash
 pip install plum-dispatch
diff --git a/setup.py b/setup.py
index 373ce8f2..7d9044dc 100755
--- a/setup.py
+++ b/setup.py
@@ -4,7 +4,7 @@
 
 setup(
     packages=find_packages(exclude=["docs"]),
-    python_requires=">=3.6",
+    python_requires=">=3.7",
     install_requires=requirements,
     ext_modules=[Extension("plum.function", ["plum/function.py"])],
     include_package_data=True,
diff --git a/tests/dispatcher/test_future_annotations.py b/tests/dispatcher/test_future_annotations.py
index b857b8d2..1582d793 100644
--- a/tests/dispatcher/test_future_annotations.py
+++ b/tests/dispatcher/test_future_annotations.py
@@ -14,7 +14,7 @@ def __init__(self, value):
         self.value = value
 
     @dispatch
-    def __add__(self, other: Union[Number, int]) -> "Number":
+    def __add__(self, other: Union[Number, int]) -> Number:
         if isinstance(other, int):
             other_value = other
         else: