diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index 71ce921288f..128aea99c02 100644
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -1174,3 +1174,18 @@ char *string_replace_char(char *str, char old_char, char new_char) {
 
         return str;
 }
+
+size_t strspn_from_end(const char *str, const char *accept) {
+        size_t n = 0;
+
+        if (isempty(str))
+                return 0;
+
+        if (isempty(accept))
+                return 0;
+
+        for (const char *p = str + strlen(str); p > str && strchr(accept, p[-1]); p--)
+                n++;
+
+        return n;
+}
diff --git a/src/basic/string-util.h b/src/basic/string-util.h
index b871224f7b6..60e80484a34 100644
--- a/src/basic/string-util.h
+++ b/src/basic/string-util.h
@@ -235,3 +235,5 @@ static inline int string_contains_word(const char *string, const char *separator
 bool streq_skip_trailing_chars(const char *s1, const char *s2, const char *ok);
 
 char *string_replace_char(char *str, char old_char, char new_char);
+
+size_t strspn_from_end(const char *str, const char *accept);
diff --git a/src/test/test-string-util.c b/src/test/test-string-util.c
index 63bb74ac106..00163d501ec 100644
--- a/src/test/test-string-util.c
+++ b/src/test/test-string-util.c
@@ -943,6 +943,18 @@ TEST(string_replace_char) {
         assert_se(streq(string_replace_char(strdupa("aaaa"), 'a', '\t'), "\t\t\t\t"));
 }
 
+TEST(strspn_from_end) {
+        assert_se(strspn_from_end(NULL, NULL) == 0);
+        assert_se(strspn_from_end("hoge", NULL) == 0);
+        assert_se(strspn_from_end(NULL, DIGITS) == 0);
+        assert_se(strspn_from_end("", DIGITS) == 0);
+        assert_se(strspn_from_end("hoge", DIGITS) == 0);
+        assert_se(strspn_from_end("1234", DIGITS) == 4);
+        assert_se(strspn_from_end("aaa1234", DIGITS) == 4);
+        assert_se(strspn_from_end("aaa1234aaa", DIGITS) == 0);
+        assert_se(strspn_from_end("aaa12aa34", DIGITS) == 2);
+}
+
 TEST(streq_skip_trailing_chars) {
         /* NULL is WHITESPACE by default*/
         assert_se(streq_skip_trailing_chars("foo bar", "foo bar", NULL));