diff --git a/tests/components/prometheus/test_init.py b/tests/components/prometheus/test_init.py
index e04cbf9e632..f187429b151 100644
--- a/tests/components/prometheus/test_init.py
+++ b/tests/components/prometheus/test_init.py
@@ -9,6 +9,7 @@ from homeassistant.components.demo.sensor import DemoSensor
 import homeassistant.components.prometheus as prometheus
 from homeassistant.const import (
     CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
+    CONTENT_TYPE_TEXT_PLAIN,
     DEGREE,
     DEVICE_CLASS_POWER,
     ENERGY_KILO_WATT_HOUR,
@@ -97,7 +98,7 @@ async def test_view(hass, hass_client):
     resp = await client.get(prometheus.API_ENDPOINT)
 
     assert resp.status == 200
-    assert resp.headers["content-type"] == "text/plain"
+    assert resp.headers["content-type"] == CONTENT_TYPE_TEXT_PLAIN
     body = await resp.text()
     body = body.split("\n")
 
diff --git a/tests/components/rest/test_sensor.py b/tests/components/rest/test_sensor.py
index 4351239064a..7fbb211fb4f 100644
--- a/tests/components/rest/test_sensor.py
+++ b/tests/components/rest/test_sensor.py
@@ -12,7 +12,7 @@ import requests_mock
 from homeassistant import config as hass_config
 import homeassistant.components.rest.sensor as rest
 import homeassistant.components.sensor as sensor
-from homeassistant.const import DATA_MEGABYTES, SERVICE_RELOAD
+from homeassistant.const import CONTENT_TYPE_TEXT_PLAIN, DATA_MEGABYTES, SERVICE_RELOAD
 from homeassistant.exceptions import PlatformNotReady
 from homeassistant.helpers.config_validation import template
 from homeassistant.setup import async_setup_component, setup_component
@@ -413,7 +413,7 @@ class TestRestSensor(unittest.TestCase):
             "rest.RestData.update",
             side_effect=self.update_side_effect(
                 "This is text rather than JSON data.",
-                CaseInsensitiveDict({"Content-Type": "text/plain"}),
+                CaseInsensitiveDict({"Content-Type": CONTENT_TYPE_TEXT_PLAIN}),
             ),
         )
         self.sensor = rest.RestSensor(
diff --git a/tests/components/rest_command/test_init.py b/tests/components/rest_command/test_init.py
index 0aee8ccfbcc..780e513ea38 100644
--- a/tests/components/rest_command/test_init.py
+++ b/tests/components/rest_command/test_init.py
@@ -4,6 +4,7 @@ import asyncio
 import aiohttp
 
 import homeassistant.components.rest_command as rc
+from homeassistant.const import CONTENT_TYPE_TEXT_PLAIN
 from homeassistant.setup import setup_component
 
 from tests.common import assert_setup_component, get_test_home_assistant
@@ -218,7 +219,7 @@ class TestRestCommandComponent:
         header_config_variations = {
             rc.DOMAIN: {
                 "no_headers_test": {},
-                "content_type_test": {"content_type": "text/plain"},
+                "content_type_test": {"content_type": CONTENT_TYPE_TEXT_PLAIN},
                 "headers_test": {
                     "headers": {
                         "Accept": "application/json",
@@ -227,14 +228,14 @@ class TestRestCommandComponent:
                 },
                 "headers_and_content_type_test": {
                     "headers": {"Accept": "application/json"},
-                    "content_type": "text/plain",
+                    "content_type": CONTENT_TYPE_TEXT_PLAIN,
                 },
                 "headers_and_content_type_override_test": {
                     "headers": {
                         "Accept": "application/json",
                         aiohttp.hdrs.CONTENT_TYPE: "application/pdf",
                     },
-                    "content_type": "text/plain",
+                    "content_type": CONTENT_TYPE_TEXT_PLAIN,
                 },
                 "headers_template_test": {
                     "headers": {
@@ -285,7 +286,7 @@ class TestRestCommandComponent:
         assert len(aioclient_mock.mock_calls[1][3]) == 1
         assert (
             aioclient_mock.mock_calls[1][3].get(aiohttp.hdrs.CONTENT_TYPE)
-            == "text/plain"
+            == CONTENT_TYPE_TEXT_PLAIN
         )
 
         # headers_test
@@ -297,7 +298,7 @@ class TestRestCommandComponent:
         assert len(aioclient_mock.mock_calls[3][3]) == 2
         assert (
             aioclient_mock.mock_calls[3][3].get(aiohttp.hdrs.CONTENT_TYPE)
-            == "text/plain"
+            == CONTENT_TYPE_TEXT_PLAIN
         )
         assert aioclient_mock.mock_calls[3][3].get("Accept") == "application/json"
 
@@ -305,7 +306,7 @@ class TestRestCommandComponent:
         assert len(aioclient_mock.mock_calls[4][3]) == 2
         assert (
             aioclient_mock.mock_calls[4][3].get(aiohttp.hdrs.CONTENT_TYPE)
-            == "text/plain"
+            == CONTENT_TYPE_TEXT_PLAIN
         )
         assert aioclient_mock.mock_calls[4][3].get("Accept") == "application/json"