diff --git a/nf_core/download.py b/nf_core/download.py
index 7bbb22f32..976472a1c 100644
--- a/nf_core/download.py
+++ b/nf_core/download.py
@@ -1736,17 +1736,22 @@ def __add_additional_tags(self) -> None:
                     if self.repo.is_valid_object(anchor) and not self.repo.is_valid_object(tag):
                         try:
                             self.repo.create_tag(
-                                tag, ref=anchor, message=f"Synonynmous tag to {anchor}; added by 'nf-core download'."
+                                tag, ref=anchor, message=f"Synonynmous tag to {anchor}; added by `nf-core download`."
                             )
                             self.repo.create_head(tag, anchor)  # should heads be created as well?
                         except (GitCommandError, InvalidGitRepositoryError) as e:
                             log.error(f"[red]Additional tag(s) could not be applied:[/]\n{e}\n")
                     else:
-                        log.error(
-                            f"[red]Adding the additional tag '{tag}' to '{anchor}' failed.[/]\n Mind that '{anchor}' must be a valid git reference that resolves to a commit, while '{tag}' must not exist hitherto."
-                        )
+                        if not self.repo.is_valid_object(anchor):
+                            log.error(
+                                f"[red]Adding tag '{tag}' to '{anchor}' failed.[/]\n Mind that '{anchor}' must be a valid git reference that resolves to a commit."
+                            )
+                        if self.repo.is_valid_object(tag):
+                            log.error(
+                                f"[red]Adding tag '{tag}' to '{anchor}' failed.[/]\n Mind that '{tag}' must not exist hitherto."
+                            )
                 else:
-                    log.error(f"[red]Could not apply invalid '--tag' specification[/]: '{additional_tag}'")
+                    log.error(f"[red]Could not apply invalid `--tag` specification[/]: '{additional_tag}'")
 
     def bare_clone(self, destination):
         if self.repo:
diff --git a/tests/test_download.py b/tests/test_download.py
index 589fe6eda..3e0f11d57 100644
--- a/tests/test_download.py
+++ b/tests/test_download.py
@@ -645,7 +645,23 @@ def test_download_workflow_for_platform(self, tmp_dir, _):
         )  # indirect definition via $container variable.
 
     #
-    # Test adding custom tags to Seqera Platform download
+    # Brief test adding a single custom tag to Seqera Platform download
+    #
+    @mock.patch("nf_core.download.DownloadWorkflow.get_singularity_images")
+    @with_temporary_folder
+    def test_download_workflow_for_platform_with_one_custom_tag(self, _, tmp_dir):
+        download_obj = DownloadWorkflow(
+            pipeline="nf-core/rnaseq",
+            revision=("3.9"),
+            compress_type="none",
+            platform=True,
+            container_system=None,
+            additional_tags=("3.9=cool_revision",),
+        )
+        assert isinstance(download_obj.additional_tags, list) and len(download_obj.additional_tags) == 1
+
+    #
+    # Test adding custom tags to Seqera Platform download (full test)
     #
     @mock.patch("nf_core.download.DownloadWorkflow.get_singularity_images")
     @with_temporary_folder
@@ -707,21 +723,8 @@ def test_download_workflow_for_platform_with_custom_tags(self, _, tmp_dir):
             assert all(
                 log in self.logged_messages
                 for log in {
-                    "[red]Could not apply invalid '-a' / '--additional-tag' specification[/]: '3.9=invalid tag'",
-                    "[red]Adding the additional tag 'not_included' to '3.14.0' failed.[/]\n Mind that '3.14.0' must be a valid git reference that resolves to a commit, while 'not_included' must not exist hitherto.",
-                    "[red]Could not apply invalid '-a' / '--additional-tag' specification[/]: 'What is this?'",
+                    "[red]Could not apply invalid `--tag` specification[/]: '3.9=invalid tag'",
+                    "[red]Adding tag 'not_included' to '3.14.0' failed.[/]\n Mind that '3.14.0' must be a valid git reference that resolves to a commit.",
+                    "[red]Could not apply invalid `--tag` specification[/]: 'What is this?'",
                 }
             )
-
-    @mock.patch("nf_core.download.DownloadWorkflow.get_singularity_images")
-    @with_temporary_folder
-    def test_download_workflow_for_platform_with_one_custom_tag(self, _, tmp_dir):
-        download_obj = DownloadWorkflow(
-            pipeline="nf-core/rnaseq",
-            revision=("3.9"),
-            compress_type="none",
-            platform=True,
-            container_system=None,
-            additional_tags=("3.9=cool_revision",),
-        )
-        assert isinstance(download_obj.additional_tags, list) and len(download_obj.additional_tags) == 1