diff --git a/src/basic/path-util.c b/src/basic/path-util.c
index fe8321edce..50ba44492e 100644
--- a/src/basic/path-util.c
+++ b/src/basic/path-util.c
@@ -819,11 +819,21 @@ const char *last_path_component(const char *path) {
 int path_extract_filename(const char *p, char **ret) {
         _cleanup_free_ char *a = NULL;
         const char *c;
+        size_t n;
 
         /* Extracts the filename part (i.e. right-most component) from a path, i.e. string that passes
-         * filename_is_valid(). A wrapper around last_path_component(), but eats up trailing slashes. Returns
-         * -EADDRNOTAVAIL if specified parameter includes no filename (i.e. is "/" or so). Returns -EINVAL if
-         * not a valid path in the first place. */
+         * filename_is_valid(). A wrapper around last_path_component(), but eats up trailing
+         * slashes. Returns:
+         *
+         * -EINVAL        → if the passed in path is not a valid path
+         * -EADDRNOTAVAIL → if only a directory was specified, but no filename, i.e. the root dir itself is specified
+         * -ENOMEM        → no memory
+         *
+         * Returns >= 0 on success. If the input path has a trailing slash, returns O_DIRECTORY, to indicate
+         * the referenced file must be a directory.
+         *
+         * This function guarantees to return a fully valid filename, i.e. one that passes
+         * filename_is_valid() – this means "." and ".." are not accepted. */
 
         if (!path_is_valid(p))
                 return -EINVAL;
@@ -834,8 +844,9 @@ int path_extract_filename(const char *p, char **ret) {
                 return -EADDRNOTAVAIL;
 
         c = last_path_component(p);
+        n = strcspn(c, "/");
 
-        a = strndup(c, strcspn(c, "/"));
+        a = strndup(c, n);
         if (!a)
                 return -ENOMEM;
 
@@ -843,7 +854,7 @@ int path_extract_filename(const char *p, char **ret) {
                 return -EINVAL;
 
         *ret = TAKE_PTR(a);
-        return 0;
+        return c[n] == '/' ? O_DIRECTORY : 0;
 }
 
 int path_extract_directory(const char *p, char **ret) {
diff --git a/src/test/test-path-util.c b/src/test/test-path-util.c
index db6c1a9efa..b92a77b9f4 100644
--- a/src/test/test-path-util.c
+++ b/src/test/test-path-util.c
@@ -570,7 +570,10 @@ static void test_path_extract_filename_one(const char *input, const char *output
         int r;
 
         r = path_extract_filename(input, &k);
-        log_info("%s → %s/%s [expected: %s/%s]", strnull(input), strnull(k), strerror_safe(r), strnull(output), strerror_safe(ret));
+        log_info_errno(r, "%s → %s/%m [expected: %s/%s]",
+                       strnull(input),
+                       strnull(k), /* strerror(r) is printed via %m, to avoid that the two strerror()'s overwrite each other's buffers */
+                       strnull(output), ret < 0 ? strerror_safe(ret) : "-");
         assert_se(streq_ptr(k, output));
         assert_se(r == ret);
 }
@@ -580,7 +583,7 @@ static void test_path_extract_filename(void) {
 
         test_path_extract_filename_one(NULL, NULL, -EINVAL);
         test_path_extract_filename_one("a/b/c", "c", 0);
-        test_path_extract_filename_one("a/b/c/", "c", 0);
+        test_path_extract_filename_one("a/b/c/", "c", O_DIRECTORY);
         test_path_extract_filename_one("/", NULL, -EADDRNOTAVAIL);
         test_path_extract_filename_one("//", NULL, -EADDRNOTAVAIL);
         test_path_extract_filename_one("///", NULL, -EADDRNOTAVAIL);
@@ -589,13 +592,13 @@ static void test_path_extract_filename(void) {
         test_path_extract_filename_one("././", NULL, -EINVAL);
         test_path_extract_filename_one("././/", NULL, -EINVAL);
         test_path_extract_filename_one("/foo/a", "a", 0);
-        test_path_extract_filename_one("/foo/a/", "a", 0);
+        test_path_extract_filename_one("/foo/a/", "a", O_DIRECTORY);
         test_path_extract_filename_one("", NULL, -EINVAL);
         test_path_extract_filename_one("a", "a", 0);
-        test_path_extract_filename_one("a/", "a", 0);
+        test_path_extract_filename_one("a/", "a", O_DIRECTORY);
         test_path_extract_filename_one("/a", "a", 0);
-        test_path_extract_filename_one("/a/", "a", 0);
-        test_path_extract_filename_one("/////////////a/////////////", "a", 0);
+        test_path_extract_filename_one("/a/", "a", O_DIRECTORY);
+        test_path_extract_filename_one("/////////////a/////////////", "a", O_DIRECTORY);
         test_path_extract_filename_one("xx/.", NULL, -EINVAL);
         test_path_extract_filename_one("xx/..", NULL, -EINVAL);
         test_path_extract_filename_one("..", NULL, -EINVAL);