diff --git a/.flake8 b/.flake8
index efde3a0..2bd90f7 100644
--- a/.flake8
+++ b/.flake8
@@ -10,3 +10,4 @@ ignore = W503
 max-complexity = 10
 max-line-length = 120
 select = E,W,F,C,N
+exclude = .env,env,venv,.venv
diff --git a/.gitignore b/.gitignore
index b9597c0..4891504 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,8 @@
 __pycache__/
 .coverage
 /coverage.xml
+.env/
+.venv/
+venv/
+env/
+.vscode/
diff --git a/.prettierignore b/.prettierignore
index 79bae62..d53f2d6 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -4,3 +4,8 @@
 .licenses/
 __pycache__/
 node_modules/
+.env/
+.venv/
+env/
+venv/
+.mypy_cache/
diff --git a/action.yml b/action.yml
index d241747..4031d4c 100644
--- a/action.yml
+++ b/action.yml
@@ -7,6 +7,9 @@ inputs:
   github-token:
     description: "GitHub access token used to comment the memory usage comparison results to the PR thread"
     default: ${{ github.token }}
+  update-comment:
+    description: "when posting a report, set this to true to only update the previous report (if one exists)"
+    default: false
 runs:
   using: "docker"
   image: "Dockerfile"
diff --git a/reportsizedeltas/reportsizedeltas.py b/reportsizedeltas/reportsizedeltas.py
index b9be40c..0fb8045 100644
--- a/reportsizedeltas/reportsizedeltas.py
+++ b/reportsizedeltas/reportsizedeltas.py
@@ -31,6 +31,7 @@ def main() -> None:
         repository_name=os.environ["GITHUB_REPOSITORY"],
         sketches_reports_source=os.environ["INPUT_SKETCHES-REPORTS-SOURCE"],
         token=os.environ["INPUT_GITHUB-TOKEN"],
+        update_comment=os.environ["INPUT_UPDATE-COMMENT"] == "true",
     )
 
     report_size_deltas.report_size_deltas()
@@ -47,7 +48,7 @@ def set_verbosity(enable_verbosity: bool) -> None:
     # INFO: manually specified output and all higher log level output
     verbose_logging_level = logging.DEBUG
 
-    if type(enable_verbosity) is not bool:
+    if not isinstance(enable_verbosity, bool):
         raise TypeError
     if enable_verbosity:
         logger.setLevel(level=verbose_logging_level)
@@ -64,7 +65,7 @@ class ReportSizeDeltas:
     token -- GitHub access token
     """
 
-    report_key_beginning = "**Memory usage change @ "
+    report_key_beginning = "<!-- arduino/report-size-deltas -->\n**Memory usage change @ "
     not_applicable_indicator = "N/A"
 
     class ReportKeys:
@@ -86,10 +87,11 @@ class ReportKeys:
         sketches = "sketches"
         compilation_success = "compilation_success"
 
-    def __init__(self, repository_name: str, sketches_reports_source: str, token: str) -> None:
+    def __init__(self, repository_name: str, sketches_reports_source: str, token: str, update_comment: bool) -> None:
         self.repository_name = repository_name
         self.sketches_reports_source = sketches_reports_source
         self.token = token
+        self.update_comment = update_comment
 
     def report_size_deltas(self) -> None:
         """Comment a report of memory usage change to pull request(s)."""
@@ -167,19 +169,32 @@ def report_size_deltas_from_workflow_artifacts(self) -> None:
             page_number += 1
             page_count = api_data["page_count"]
 
-    def report_exists(self, pr_number: int, pr_head_sha: str) -> bool:
+    def report_exists(self, pr_number: int, pr_head_sha: str = "") -> str | None:
         """Return whether a report has already been commented to the pull request thread for the latest workflow run.
 
-        Keyword arguments:
-        pr_number -- number of the pull request to check
-        pr_head_sha -- PR's head branch hash
+        If `pr_head_sha` is a blank str, then all thread comments are traversed. Additionally,
+        any report comment found will be deleted if it is not the first report comment found.
+        This is designed to support the action input `update-comment` when asserted.
+
+        If `pr_head_sha` is not a blank str, then thread comments are traversed
+        until a report comment that corresponds to the commit is found.
+        No comments are deleted in this scenario.
+
+        Arguments:
+          pr_number: number of the pull request to check
+          pr_head_sha: PR's head branch hash
+        Returns:
+          - A URL str to use for PATCHing the first applicable report comment.
+          - None if no applicable report comments exist.
         """
-        # Get the pull request's comments
+        comment_url: str | None = None
+        request_uri = f"repos/{self.repository_name}/issues/{pr_number}/comments"
         page_number = 1
         page_count = 1
         while page_number <= page_count:
+            # Get the pull request's comments
             api_data = self.api_request(
-                request="repos/" + self.repository_name + "/issues/" + str(pr_number) + "/comments",
+                request=request_uri,
                 page_number=page_number,
             )
 
@@ -187,13 +202,20 @@ def report_exists(self, pr_number: int, pr_head_sha: str) -> bool:
             for comment_data in comments_data:
                 # Check if the comment is a report for the PR's head SHA
                 if comment_data["body"].startswith(self.report_key_beginning + pr_head_sha):
-                    return True
+                    if pr_head_sha:
+                        return comment_data["url"]
+                    # else: pr_head_sha == ""
+                    if comment_url is None:
+                        comment_url = comment_data["url"]
+                    else:  # found another report
+                        # delete report comment if it is not the first report found
+                        self.http_request(url=comment_data["url"], method="DELETE")
 
             page_number += 1
             page_count = api_data["page_count"]
 
         # No reports found for the PR's head SHA
-        return False
+        return comment_url
 
     def get_artifacts_data_for_sha(self, pr_user_login: str, pr_head_ref: str, pr_head_sha: str):
         """Return the list of data objects for the report artifacts associated with the given head commit hash.
@@ -534,7 +556,10 @@ def comment_report(self, pr_number: int, report_markdown: str) -> None:
         report_data = json.dumps(obj={"body": report_markdown}).encode(encoding="utf-8")
         url = "https://api.github.com/repos/" + self.repository_name + "/issues/" + str(pr_number) + "/comments"
 
-        self.http_request(url=url, data=report_data)
+        comment_url = None if not self.update_comment else self.report_exists(pr_number=pr_number)
+        method = "PATCH" if comment_url else None
+
+        self.http_request(url=comment_url or url, data=report_data, method=method)
 
     def api_request(self, request: str, request_parameters: str = "", page_number: int = 1):
         """Do a GitHub API request. Return a dictionary containing:
@@ -594,7 +619,7 @@ def get_json_response(self, url: str):
         except Exception as exception:
             raise exception
 
-    def http_request(self, url: str, data: bytes | None = None):
+    def http_request(self, url: str, data: bytes | None = None, method: str | None = None):
         """Make a request and return a dictionary:
         read -- the response
         info -- headers
@@ -604,28 +629,32 @@ def http_request(self, url: str, data: bytes | None = None):
         url -- the URL to load
         data -- data to pass with the request
                 (default value: None)
+        method -- the HTTP request method to use
+                  (default is None which means ``'GET' if data is None else 'POST'``).
         """
-        with self.raw_http_request(url=url, data=data) as response_object:
+        with self.raw_http_request(url=url, data=data, method=method) as response_object:
             return {
                 "body": response_object.read().decode(encoding="utf-8", errors="ignore"),
                 "headers": response_object.info(),
                 "url": response_object.geturl(),
             }
 
-    def raw_http_request(self, url: str, data: bytes | None = None):
+    def raw_http_request(self, url: str, data: bytes | None = None, method: str | None = None):
         """Make a request and return an object containing the response.
 
         Keyword arguments:
         url -- the URL to load
         data -- data to pass with the request
                 (default value: None)
+        method -- the HTTP request method to use
+                  (default is None which means ``'GET' if data is None else 'POST'``).
         """
         # Maximum times to retry opening the URL before giving up
         maximum_urlopen_retries = 3
 
         logger.info("Opening URL: " + url)
 
-        request = urllib.request.Request(url=url, data=data)
+        request = urllib.request.Request(url=url, data=data, method=method)
         request.add_unredirected_header(key="Accept", val="application/vnd.github+json")
         request.add_unredirected_header(key="Authorization", val="Bearer " + self.token)
         request.add_unredirected_header(key="User-Agent", val=self.repository_name.split("/")[0])
diff --git a/reportsizedeltas/tests/data/test_delete_previous_comment/comments.json b/reportsizedeltas/tests/data/test_delete_previous_comment/comments.json
new file mode 100644
index 0000000..fbb69eb
--- /dev/null
+++ b/reportsizedeltas/tests/data/test_delete_previous_comment/comments.json
@@ -0,0 +1,22 @@
+[
+  {
+    "url": "https://api.github.com/repos/test-user/test-repo/issues/comments/1953679626",
+    "body": "<!-- arduino/report-size-deltas -->\n**Memory usage change @ 525def8e855e5f227a4b4a0b6f84c34cd288a5ea**\n\nBoard|flash|%|RAM for global variables|%\n-|-|-|-|-\n`arduino:avr:nano`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n`arduino:samd:mkrzero`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n\n<details>\n<summary>Click for full report table</summary>\n\nBoard|`examples/Getting_Started_SimpleClient_Mesh`<br>flash|%|`examples/Getting_Started_SimpleClient_Mesh`<br>RAM for global variables|%|`examples/Getting_Started_SimpleServer_Mesh`<br>flash|%|`examples/Getting_Started_SimpleServer_Mesh`<br>RAM for global variables|%|`examples/InteractiveServer_Mesh`<br>flash|%|`examples/InteractiveServer_Mesh`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic`<br>flash|%|`examples/MQTT/mqtt_basic`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic_2`<br>flash|%|`examples/MQTT/mqtt_basic_2`<br>RAM for global variables|%|`examples/SimpleClient_Mesh`<br>flash|%|`examples/SimpleClient_Mesh`<br>RAM for global variables|%\n-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-\n`arduino:avr:nano`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n`arduino:samd:mkrzero`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n\n</details>\n\n<details>\n<summary>Click for full report CSV</summary>\n\n```\nBoard,examples/Getting_Started_SimpleClient_Mesh<br>flash,%,examples/Getting_Started_SimpleClient_Mesh<br>RAM for global variables,%,examples/Getting_Started_SimpleServer_Mesh<br>flash,%,examples/Getting_Started_SimpleServer_Mesh<br>RAM for global variables,%,examples/InteractiveServer_Mesh<br>flash,%,examples/InteractiveServer_Mesh<br>RAM for global variables,%,examples/MQTT/mqtt_basic<br>flash,%,examples/MQTT/mqtt_basic<br>RAM for global variables,%,examples/MQTT/mqtt_basic_2<br>flash,%,examples/MQTT/mqtt_basic_2<br>RAM for global variables,%,examples/SimpleClient_Mesh<br>flash,%,examples/SimpleClient_Mesh<br>RAM for global variables,%\narduino:avr:nano,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\narduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\n```\n</details>"
+  },
+  {
+    "url": "https://api.github.com/repos/test-user/test-repo/issues/comments/1953996601",
+    "body": "<!-- arduino/report-size-deltas -->\n**Memory usage change @ 862a917fe24c6f737abc336b681b7326c0fcceec**\n\nBoard|flash|%|RAM for global variables|%\n-|-|-|-|-\n`arduino:avr:nano`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n`arduino:samd:mkrzero`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n\n<details>\n<summary>Click for full report table</summary>\n\nBoard|`examples/Getting_Started_SimpleClient_Mesh`<br>flash|%|`examples/Getting_Started_SimpleClient_Mesh`<br>RAM for global variables|%|`examples/Getting_Started_SimpleServer_Mesh`<br>flash|%|`examples/Getting_Started_SimpleServer_Mesh`<br>RAM for global variables|%|`examples/InteractiveServer_Mesh`<br>flash|%|`examples/InteractiveServer_Mesh`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic`<br>flash|%|`examples/MQTT/mqtt_basic`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic_2`<br>flash|%|`examples/MQTT/mqtt_basic_2`<br>RAM for global variables|%|`examples/SimpleClient_Mesh`<br>flash|%|`examples/SimpleClient_Mesh`<br>RAM for global variables|%\n-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-\n`arduino:avr:nano`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n`arduino:samd:mkrzero`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n\n</details>\n\n<details>\n<summary>Click for full report CSV</summary>\n\n```\nBoard,examples/Getting_Started_SimpleClient_Mesh<br>flash,%,examples/Getting_Started_SimpleClient_Mesh<br>RAM for global variables,%,examples/Getting_Started_SimpleServer_Mesh<br>flash,%,examples/Getting_Started_SimpleServer_Mesh<br>RAM for global variables,%,examples/InteractiveServer_Mesh<br>flash,%,examples/InteractiveServer_Mesh<br>RAM for global variables,%,examples/MQTT/mqtt_basic<br>flash,%,examples/MQTT/mqtt_basic<br>RAM for global variables,%,examples/MQTT/mqtt_basic_2<br>flash,%,examples/MQTT/mqtt_basic_2<br>RAM for global variables,%,examples/SimpleClient_Mesh<br>flash,%,examples/SimpleClient_Mesh<br>RAM for global variables,%\narduino:avr:nano,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\narduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\n```\n</details>"
+  },
+  {
+    "url": "https://api.github.com/repos/test-user/test-repo/issues/comments/1954284300",
+    "body": "<!-- arduino/report-size-deltas -->\n**Memory usage change @ 0098017901c516c6cd49e248f1aabd6b30c91aa9**\n\nBoard|flash|%|RAM for global variables|%\n-|-|-|-|-\n`arduino:avr:nano`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n`arduino:samd:mkrzero`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n\n<details>\n<summary>Click for full report table</summary>\n\nBoard|`examples/Getting_Started_SimpleClient_Mesh`<br>flash|%|`examples/Getting_Started_SimpleClient_Mesh`<br>RAM for global variables|%|`examples/Getting_Started_SimpleServer_Mesh`<br>flash|%|`examples/Getting_Started_SimpleServer_Mesh`<br>RAM for global variables|%|`examples/InteractiveServer_Mesh`<br>flash|%|`examples/InteractiveServer_Mesh`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic`<br>flash|%|`examples/MQTT/mqtt_basic`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic_2`<br>flash|%|`examples/MQTT/mqtt_basic_2`<br>RAM for global variables|%|`examples/SimpleClient_Mesh`<br>flash|%|`examples/SimpleClient_Mesh`<br>RAM for global variables|%\n-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-\n`arduino:avr:nano`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n`arduino:samd:mkrzero`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n\n</details>\n\n<details>\n<summary>Click for full report CSV</summary>\n\n```\nBoard,examples/Getting_Started_SimpleClient_Mesh<br>flash,%,examples/Getting_Started_SimpleClient_Mesh<br>RAM for global variables,%,examples/Getting_Started_SimpleServer_Mesh<br>flash,%,examples/Getting_Started_SimpleServer_Mesh<br>RAM for global variables,%,examples/InteractiveServer_Mesh<br>flash,%,examples/InteractiveServer_Mesh<br>RAM for global variables,%,examples/MQTT/mqtt_basic<br>flash,%,examples/MQTT/mqtt_basic<br>RAM for global variables,%,examples/MQTT/mqtt_basic_2<br>flash,%,examples/MQTT/mqtt_basic_2<br>RAM for global variables,%,examples/SimpleClient_Mesh<br>flash,%,examples/SimpleClient_Mesh<br>RAM for global variables,%\narduino:avr:nano,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\narduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\n```\n</details>"
+  },
+  {
+    "url": "https://api.github.com/repos/test-user/test-repo/issues/comments/1955441026",
+    "body": "<!-- arduino/report-size-deltas -->\n**Memory usage change @ f9881f578cf28800a2076ae709434249e9cb9d67**\n\nBoard|flash|%|RAM for global variables|%\n-|-|-|-|-\n`arduino:avr:nano`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n`arduino:samd:mkrzero`|0 - 0|0.0 - 0.0|0 - 0|0.0 - 0.0\n\n<details>\n<summary>Click for full report table</summary>\n\nBoard|`examples/Getting_Started_SimpleClient_Mesh`<br>flash|%|`examples/Getting_Started_SimpleClient_Mesh`<br>RAM for global variables|%|`examples/Getting_Started_SimpleServer_Mesh`<br>flash|%|`examples/Getting_Started_SimpleServer_Mesh`<br>RAM for global variables|%|`examples/InteractiveServer_Mesh`<br>flash|%|`examples/InteractiveServer_Mesh`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic`<br>flash|%|`examples/MQTT/mqtt_basic`<br>RAM for global variables|%|`examples/MQTT/mqtt_basic_2`<br>flash|%|`examples/MQTT/mqtt_basic_2`<br>RAM for global variables|%|`examples/SimpleClient_Mesh`<br>flash|%|`examples/SimpleClient_Mesh`<br>RAM for global variables|%\n-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-\n`arduino:avr:nano`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n`arduino:samd:mkrzero`|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0|0|0.0\n\n</details>\n\n<details>\n<summary>Click for full report CSV</summary>\n\n```\nBoard,examples/Getting_Started_SimpleClient_Mesh<br>flash,%,examples/Getting_Started_SimpleClient_Mesh<br>RAM for global variables,%,examples/Getting_Started_SimpleServer_Mesh<br>flash,%,examples/Getting_Started_SimpleServer_Mesh<br>RAM for global variables,%,examples/InteractiveServer_Mesh<br>flash,%,examples/InteractiveServer_Mesh<br>RAM for global variables,%,examples/MQTT/mqtt_basic<br>flash,%,examples/MQTT/mqtt_basic<br>RAM for global variables,%,examples/MQTT/mqtt_basic_2<br>flash,%,examples/MQTT/mqtt_basic_2<br>RAM for global variables,%,examples/SimpleClient_Mesh<br>flash,%,examples/SimpleClient_Mesh<br>RAM for global variables,%\narduino:avr:nano,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\narduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0\n```\n</details>"
+  },
+  {
+    "url": "https://api.github.com/repos/test-user/test-repo/issues/comments/1955465432",
+    "body": "**Memory usage change @ NOT A BOT COMMENT"
+  }
+]
diff --git a/reportsizedeltas/tests/test_reportsizedeltas.py b/reportsizedeltas/tests/test_reportsizedeltas.py
index 4fe96cd..e668ad8 100644
--- a/reportsizedeltas/tests/test_reportsizedeltas.py
+++ b/reportsizedeltas/tests/test_reportsizedeltas.py
@@ -1,4 +1,4 @@
-import distutils.dir_util
+import shutil
 import filecmp
 import json
 import os
@@ -22,6 +22,7 @@ def get_reportsizedeltas_object(
     repository_name: str = "FooOwner/BarRepository",
     sketches_reports_source: str = "foo-artifact-pattern",
     token: str = "foo token",
+    update_comment: bool = False,
 ) -> reportsizedeltas.ReportSizeDeltas:
     """Return a reportsizedeltas.ReportSizeDeltas object to use in tests.
 
@@ -32,7 +33,10 @@ def get_reportsizedeltas_object(
     token -- GitHub access token
     """
     return reportsizedeltas.ReportSizeDeltas(
-        repository_name=repository_name, sketches_reports_source=sketches_reports_source, token=token
+        repository_name=repository_name,
+        sketches_reports_source=sketches_reports_source,
+        token=token,
+        update_comment=update_comment,
     )
 
 
@@ -106,10 +110,12 @@ class ActionInputs:
         repository_name = "GoldenOwner/GoldenRepository"
         sketches_reports_source = "golden-source-pattern"
         token = "golden-github-token"
+        update_comment = "false"
 
     monkeypatch.setenv("GITHUB_REPOSITORY", ActionInputs.repository_name)
     monkeypatch.setenv("INPUT_SKETCHES-REPORTS-SOURCE", ActionInputs.sketches_reports_source)
     monkeypatch.setenv("INPUT_GITHUB-TOKEN", ActionInputs.token)
+    monkeypatch.setenv("INPUT_UPDATE-COMMENT", ActionInputs.update_comment)
 
     return ActionInputs()
 
@@ -132,6 +138,7 @@ def report_size_deltas(self):
         repository_name=setup_environment_variables.repository_name,
         sketches_reports_source=setup_environment_variables.sketches_reports_source,
         token=setup_environment_variables.token,
+        update_comment=setup_environment_variables.update_comment == "true",
     )
     ReportSizeDeltas.report_size_deltas.assert_called_once()
 
@@ -360,18 +367,47 @@ def test_report_exists():
 
     report_size_deltas = get_reportsizedeltas_object(repository_name=repository_name)
 
-    json_data = [{"body": "foo123"}, {"body": report_size_deltas.report_key_beginning + pr_head_sha + "foo"}]
+    json_data = [
+        {"body": "foo123"},
+        {"body": report_size_deltas.report_key_beginning + pr_head_sha + "foo", "url": "some/url"},
+    ]
     report_size_deltas.api_request = unittest.mock.MagicMock(
         return_value={"json_data": json_data, "additional_pages": False, "page_count": 1}
     )
 
-    assert report_size_deltas.report_exists(pr_number=pr_number, pr_head_sha=pr_head_sha)
+    assert json_data[1]["url"] == report_size_deltas.report_exists(pr_number=pr_number, pr_head_sha=pr_head_sha)
 
     report_size_deltas.api_request.assert_called_once_with(
         request="repos/" + repository_name + "/issues/" + str(pr_number) + "/comments", page_number=1
     )
 
-    assert not report_size_deltas.report_exists(pr_number=pr_number, pr_head_sha="asdf")
+    assert report_size_deltas.report_exists(pr_number=pr_number, pr_head_sha="asdf") is None
+
+
+def test_delete_previous_comment():
+    pr_number = 42
+    repository_name = "test_user/test_repo"
+
+    report_size_deltas = get_reportsizedeltas_object(repository_name=repository_name)
+
+    json_comments = json.loads((test_data_path / "test_delete_previous_comment" / "comments.json").read_bytes())
+
+    report_size_deltas.http_request = unittest.mock.Mock()
+    report_size_deltas.get_json_response = unittest.mock.Mock(
+        return_value={"json_data": json_comments, "page_count": 1},
+    )
+
+    comment_url = report_size_deltas.report_exists(pr_number=pr_number)
+    assert comment_url == json_comments[0]["url"]
+
+    for comment in json_comments[1:4]:
+        if comment["body"].startswith(report_size_deltas.report_key_beginning):
+            report_size_deltas.http_request.assert_any_call(url=comment["url"], method="DELETE")
+
+    # It would be nicer to assert that a call has not been made.
+    # Here, we just assert that only the last 3 out of 4 bot comments were deleted.
+    # Implicitly, this also means the non-bot comment (`json_comment[4]`) was not deleted.
+    assert report_size_deltas.http_request.call_count == 3
 
 
 def test_get_artifacts_data_for_sha():
@@ -526,8 +562,8 @@ def test_get_sketches_reports(test_data_folder_name):
 
     artifacts_folder_object = tempfile.TemporaryDirectory(prefix="test_reportsizedeltas-")
     try:
-        distutils.dir_util.copy_tree(
-            src=str(current_test_data_path.joinpath("artifacts")), dst=artifacts_folder_object.name
+        shutil.copytree(
+            src=str(current_test_data_path.joinpath("artifacts")), dst=artifacts_folder_object.name, dirs_exist_ok=True
         )
     except Exception:  # pragma: no cover
         artifacts_folder_object.cleanup()
@@ -699,6 +735,7 @@ def test_add_detailed_report_row(report_data, fqbn_data, expected_report_data):
 def test_generate_report():
     sketches_report_path = test_data_path.joinpath("size-deltas-reports-new")
     expected_deltas_report = (
+        "<!-- arduino/report-size-deltas -->\n"
         "**Memory usage change @ d8fd302**\n\n"
         "Board|flash|%|RAM for global variables|%\n"
         "-|-|-|-|-\n"
@@ -730,7 +767,7 @@ def test_generate_report():
 
     artifacts_folder_object = tempfile.TemporaryDirectory(prefix="test_reportsizedeltas-")
     try:
-        distutils.dir_util.copy_tree(src=str(sketches_report_path), dst=artifacts_folder_object.name)
+        shutil.copytree(src=str(sketches_report_path), dst=artifacts_folder_object.name, dirs_exist_ok=True)
     except Exception:  # pragma: no cover
         artifacts_folder_object.cleanup()
         raise
@@ -778,6 +815,7 @@ def test_comment_report():
     report_size_deltas.http_request.assert_called_once_with(
         url="https://api.github.com/repos/" + repository_name + "/issues/" + str(pr_number) + "/comments",
         data=report_data,
+        method=None,
     )
 
 
@@ -868,7 +906,7 @@ def test_http_request():
 
     report_size_deltas.http_request(url=url, data=data)
 
-    report_size_deltas.raw_http_request.assert_called_once_with(url=url, data=data)
+    report_size_deltas.raw_http_request.assert_called_once_with(url=url, data=data, method=None)
 
 
 def test_raw_http_request(mocker):
@@ -896,6 +934,7 @@ def add_unredirected_header(self):
     urllib.request.Request.assert_called_once_with(
         url=url,
         data=data,
+        method=None,
     )
     request.add_unredirected_header.assert_has_calls(
         calls=[