diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index 7033cf8..c05faa7 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -15,7 +15,7 @@ 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
diff --git a/setup.py b/setup.py
index 99f057c..20da3f8 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="strsimpy",
-    version="0.1.9",
+    version="0.2.1",
     description="A library implementing different string similarity and distance measures",
     long_description=long_description,
     long_description_content_type="text/markdown",
@@ -22,6 +22,7 @@
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
     )
diff --git a/strsimpy/__init__.py b/strsimpy/__init__.py
index 1e10460..1b1792f 100644
--- a/strsimpy/__init__.py
+++ b/strsimpy/__init__.py
@@ -37,4 +37,4 @@
 from .sift4 import SIFT4Options, SIFT4
 
 __name__ = 'strsimpy'
-__version__ = '0.1.9'
+__version__ = '0.2.1'
diff --git a/strsimpy/ngram.py b/strsimpy/ngram.py
index c3860b7..27d4ae1 100644
--- a/strsimpy/ngram.py
+++ b/strsimpy/ngram.py
@@ -46,7 +46,7 @@ def distance(self, s0, s1):
             for i in range(min(sl, tl)):
                 if s0[i] == s1[i]:
                     cost += 1
-            return 1.0 * cost / max(sl, tl)
+            return 1.0 - cost / max(sl, tl)
 
         sa = [''] * (sl + self.n - 1)
 
diff --git a/strsimpy/sift4_test.py b/strsimpy/sift4_test.py
index 039d8b5..1960e7b 100644
--- a/strsimpy/sift4_test.py
+++ b/strsimpy/sift4_test.py
@@ -14,7 +14,7 @@ def testSIFT4(self):
         ]
 
         for a, b, offset, res in results:
-            self.assertEquals(res, s.distance(a, b, maxoffset=offset))
+            self.assertEqual(res, s.distance(a, b, maxoffset=offset))
 
 
 if __name__ == "__main__":