diff --git a/src/darker/__main__.py b/src/darker/__main__.py
index ba65e93fb..8fba15a38 100644
--- a/src/darker/__main__.py
+++ b/src/darker/__main__.py
@@ -29,8 +29,8 @@ def format_edited_parts(
     """Black (and optional isort) formatting for chunks with edits since the last commit
 
     1. run isort on each edited file (optional)
-    2. diff HEAD and worktree (optionally with isort modifications) for all file & dir
-       paths on the command line
+    2. diff the given revision and worktree (optionally with isort modifications) for
+       all file & dir paths on the command line
     3. extract line numbers in each edited to-file for changed lines
     4. run black on the contents of each edited to-file
     5. get a diff between the edited to-file and the reformatted content
@@ -44,8 +44,8 @@ def format_edited_parts(
        the original edited to-file
     10. write the reformatted source back to the original file
     11. run linter subprocesses for all edited files (11.-14. optional)
-    12. diff HEAD and worktree (after isort and Black reformatting) for each file
-        reported by a linter
+    12. diff the given revision and worktree (after isort and Black reformatting) for
+        each file reported by a linter
     13. extract line numbers in each file reported by a linter for changed lines
     14. print only linter error lines which fall on changed lines
 
@@ -80,7 +80,7 @@ def format_edited_parts(
         edited_lines = edited_content.splitlines()
         max_context_lines = len(edited_lines)
         for context_lines in range(max_context_lines + 1):
-            # 2. diff HEAD and worktree for the file
+            # 2. diff the given revision and worktree for the file
             # 3. extract line numbers in the edited to-file for changed lines
             edited_linenums = edited_linenums_differ.revision_vs_lines(
                 path_in_repo, edited_lines, context_lines
@@ -145,8 +145,8 @@ def format_edited_parts(
                     yield src, worktree_content, result_str, chosen_lines
                 break
     # 11. run linter subprocesses for all edited files (11.-14. optional)
-    # 12. diff HEAD and worktree (after isort and Black reformatting) for each file
-    #     reported by a linter
+    # 12. diff the given revision and worktree (after isort and Black reformatting) for
+    #     each file reported by a linter
     # 13. extract line numbers in each file reported by a linter for changed lines
     # 14. print only linter error lines which fall on changed lines
     for linter_cmdline in linter_cmdlines:
diff --git a/src/darker/git.py b/src/darker/git.py
index fa9dbaef8..0381a280a 100644
--- a/src/darker/git.py
+++ b/src/darker/git.py
@@ -102,7 +102,7 @@ class EditedLinenumsDiffer:
 
     @lru_cache(maxsize=1)
     def revision_vs_worktree(self, path_in_repo: Path, context_lines: int) -> List[int]:
-        """Return numbers of lines changed between HEAD and the working tree"""
+        """Return numbers of lines changed between a given revision and the worktree"""
         lines = (self.git_root / path_in_repo).read_text("utf-8").splitlines()
         return self.revision_vs_lines(path_in_repo, lines, context_lines)
 
diff --git a/src/darker/tests/test_git.py b/src/darker/tests/test_git.py
index 787d771b7..9ec0feb73 100644
--- a/src/darker/tests/test_git.py
+++ b/src/darker/tests/test_git.py
@@ -101,8 +101,8 @@ def test_git_get_modified_files(git_repo, modify_paths, paths, expect):
 
 
 @edited_linenums_differ_cases
-def test_edited_linenums_differ_head_vs_worktree(git_repo, context_lines, expect):
-    """Tests for EditedLinenumsDiffer.head_vs_worktree()"""
+def test_edited_linenums_differ_revision_vs_worktree(git_repo, context_lines, expect):
+    """Tests for EditedLinenumsDiffer.revision_vs_worktree()"""
     paths = git_repo.add({"a.py": "1\n2\n3\n4\n5\n6\n7\n8\n"}, commit="Initial commit")
     paths["a.py"].write("1\n2\nthree\n4\n5\n6\nseven\n8\n")
     differ = EditedLinenumsDiffer(git_repo.root)
@@ -113,9 +113,12 @@ def test_edited_linenums_differ_head_vs_worktree(git_repo, context_lines, expect
 
 
 @edited_linenums_differ_cases
-def test_edited_linenums_differ_head_vs_lines(git_repo, context_lines, expect):
+def test_edited_linenums_differ_revision_vs_lines(git_repo, context_lines, expect):
+    """Tests for EditedLinenumsDiffer.revision_vs_lines()"""
     git_repo.add({'a.py': '1\n2\n3\n4\n5\n6\n7\n8\n'}, commit='Initial commit')
     lines = ['1', '2', 'three', '4', '5', '6', 'seven', '8']
     differ = EditedLinenumsDiffer(git_repo.root)
+
     result = differ.revision_vs_lines(Path("a.py"), lines, context_lines)
+
     assert result == expect