diff --git a/src/tree.c b/src/tree.c
index 7b47af347..6f9838880 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -26,7 +26,9 @@ static bool valid_filemode(const int filemode)
 
 static int valid_entry_name(const char *filename)
 {
-	return *filename != '\0' && strchr(filename, '/') == NULL;
+	return *filename != '\0' && strchr(filename, '/') == NULL &&
+		strcmp(filename, "..") != 0 && strcmp(filename, ".") != 0 &&
+		strcmp(filename, ".git") != 0;
 }
 
 static int entry_sort_cmp(const void *a, const void *b)
@@ -372,6 +374,9 @@ static int append_entry(
 {
 	git_tree_entry *entry;
 
+	if (!valid_entry_name(filename))
+		return tree_error("Failed to insert entry. Invalid name for a tree entry");
+
 	entry = alloc_entry(filename);
 	GITERR_CHECK_ALLOC(entry);
 
diff --git a/tests-clar/index/tests.c b/tests-clar/index/tests.c
index d3f6f2582..3b71b704d 100644
--- a/tests-clar/index/tests.c
+++ b/tests-clar/index/tests.c
@@ -261,3 +261,30 @@ void test_index_tests__add_from_workdir_to_a_bare_repository_returns_EBAREPO(voi
 	git_index_free(index);
 	git_repository_free(bare_repo);
 }
+
+/* Test that writing an invalid filename fails */
+void test_index_tests__write_invalid_filename(void)
+{
+	git_repository *repo;
+	git_index *index;
+	git_oid expected;
+
+	p_mkdir("read_tree", 0700);
+
+	cl_git_pass(git_repository_init(&repo, "./read_tree", 0));
+	cl_git_pass(git_repository_index(&index, repo));
+
+	cl_assert(git_index_entrycount(index) == 0);
+
+	cl_git_mkfile("./read_tree/.git/hello", NULL);
+
+	cl_git_pass(git_index_add_from_workdir(index, ".git/hello"));
+
+	/* write-tree */
+	cl_git_fail(git_index_write_tree(&expected, index));
+
+	git_index_free(index);
+	git_repository_free(repo);
+
+	cl_fixture_cleanup("read_tree");
+}
diff --git a/tests-clar/object/tree/write.c b/tests-clar/object/tree/write.c
index 657bed289..cc5438b05 100644
--- a/tests-clar/object/tree/write.c
+++ b/tests-clar/object/tree/write.c
@@ -39,6 +39,12 @@ void test_object_tree_write__from_memory(void)
 		&bid, GIT_FILEMODE_BLOB));
 	cl_git_fail(git_treebuilder_insert(NULL, builder, "/",
 		&bid, GIT_FILEMODE_BLOB));
+	cl_git_fail(git_treebuilder_insert(NULL, builder, ".git",
+		&bid, GIT_FILEMODE_BLOB));
+	cl_git_fail(git_treebuilder_insert(NULL, builder, "..",
+		&bid, GIT_FILEMODE_BLOB));
+	cl_git_fail(git_treebuilder_insert(NULL, builder, ".",
+		&bid, GIT_FILEMODE_BLOB));
 	cl_git_fail(git_treebuilder_insert(NULL, builder, "folder/new.txt",
 		&bid, GIT_FILEMODE_BLOB));