diff --git a/pathspec/util.py b/pathspec/util.py
index 52782d4..c108644 100644
--- a/pathspec/util.py
+++ b/pathspec/util.py
@@ -171,7 +171,7 @@ def detailed_match_files(
 			else:
 				# Remove files.
 				for file in result_files:
-					del return_files[file]
+					return_files.pop(file, None)
 
 	return return_files
 
diff --git a/tests/test_01_util.py b/tests/test_01_util.py
index b0e4ff8..a24f13a 100644
--- a/tests/test_01_util.py
+++ b/tests/test_01_util.py
@@ -26,6 +26,7 @@
 from pathspec.util import (
 	RecursionError,
 	check_match_file,
+	detailed_match_files,
 	iter_tree_entries,
 	iter_tree_files,
 	match_file,
@@ -115,6 +116,30 @@ def test_02_many(self):
 		})
 
 
+class DetailedMatchFilesTest(unittest.TestCase):
+	"""Test inclusion and exclusion bookkeeping for detailed matches."""
+
+	def test_negation_without_previous_match(self):
+		patterns = list(map(GitIgnoreBasicPattern, ['*.txt', '!*.log']))
+		for all_matches in (False, True):
+			with self.subTest(all_matches=all_matches):
+				results = detailed_match_files(patterns, ['notes.txt', 'debug.log'], all_matches)
+				self.assertEqual(set(results), {'notes.txt'})
+				self.assertEqual(results['notes.txt'].patterns, [patterns[0]])
+
+	def test_repeated_negation_and_reinclusion(self):
+		patterns = list(map(GitIgnoreBasicPattern, ['*.txt', '!notes.txt', '!notes.txt', 'notes.txt']))
+		for all_matches in (False, True):
+			with self.subTest(all_matches=all_matches):
+				results = detailed_match_files(iter(patterns), iter(['notes.txt']), all_matches)
+				self.assertEqual(set(results), {'notes.txt'})
+				self.assertEqual(results['notes.txt'].patterns, [patterns[-1]])
+
+	def test_negation_removes_previous_match(self):
+		patterns = list(map(GitIgnoreBasicPattern, ['*.txt', '!notes.txt']))
+		self.assertEqual(detailed_match_files(patterns, ['notes.txt']), {})
+
+
 class IterTreeTest(unittest.TestCase):
 	"""
 	The :class:`IterTreeTest` class tests :meth:`.iter_tree_entries` and