diff --git a/tests/samples/output/test_help_contents b/tests/samples/output/test_help_contents
index c2eea17..91ff1eb 100644
--- a/tests/samples/output/test_help_contents
+++ b/tests/samples/output/test_help_contents
@@ -22,8 +22,8 @@ optional arguments:
                         "domain" or "app". Defaults to "file".
   --category CATEGORY   Category of this heartbeat activity. Can be "coding",
                         "building", "indexing", "debugging", "running tests",
-                        "manual testing", "browsing", "code reviewing" or
-                        "designing". Defaults to "coding".
+                        "writing tests", "manual testing", "code reviewing",
+                        "browsing", or "designing". Defaults to "coding".
   --proxy PROXY         Optional proxy configuration. Supports HTTPS and SOCKS
                         proxies. For example: https://user:pass@host:port or
                         socks5://user:pass@host:port or domain\user:pass
diff --git a/tests/test_arguments.py b/tests/test_arguments.py
index fd641e2..8884b08 100644
--- a/tests/test_arguments.py
+++ b/tests/test_arguments.py
@@ -601,6 +601,7 @@ class ArgumentsTestCase(TestCase):
                 'debugging',
                 'running tests',
                 'manual testing',
+                'writing tests',
                 'browsing',
                 'code reviewing',
                 'designing',
diff --git a/wakatime/arguments.py b/wakatime/arguments.py
index 34bd999..140393c 100644
--- a/wakatime/arguments.py
+++ b/wakatime/arguments.py
@@ -89,8 +89,8 @@ def parse_arguments():
                         help='Category of this heartbeat activity. Can be ' +
                              '"coding", "building", "indexing", ' +
                              '"debugging", "running tests", ' +
-                             '"manual testing", "browsing", ' +
-                             '"code reviewing" or "designing". ' +
+                             '"writing tests", "manual testing", ' +
+                             '"code reviewing", "browsing", or "designing". ' +
                              'Defaults to "coding".')
     parser.add_argument('--proxy', dest='proxy', action=StoreWithoutQuotes,
                         help='Optional proxy configuration. Supports HTTPS '+
diff --git a/wakatime/heartbeat.py b/wakatime/heartbeat.py
index 7adbde0..ef53fdf 100644
--- a/wakatime/heartbeat.py
+++ b/wakatime/heartbeat.py
@@ -70,6 +70,7 @@ class Heartbeat(object):
             'debugging',
             'running tests',
             'manual testing',
+            'writing tests',
             'browsing',
             'code reviewing',
             'designing',