diff --git a/m-string.h b/m-string.h
index 26fe4f84..dca7aff4 100644
--- a/m-string.h
+++ b/m-string.h
@@ -436,6 +436,15 @@ string_cspn(const string_t v1, const char accept[])
   return strcspn(string_get_cstr(v1), accept);
 }
 
+static inline size_t
+string_pbrk(const string_t v1, const char first_of[])
+{
+  STRING_CONTRACT (v1);
+  M_ASSUME (first_of != NULL);
+  const char *p = M_ASSIGN_CAST(const char*, strpbrk(string_get_cstr(v1), first_of));
+  return p == NULL ? STRING_FAILURE : (size_t) (p-string_get_cstr(v1));
+}
+
 static inline void
 string_left(string_t v, size_t index)
 {
diff --git a/tests/test-mstring.c b/tests/test-mstring.c
index 311987ae..a911c313 100644
--- a/tests/test-mstring.c
+++ b/tests/test-mstring.c
@@ -318,6 +318,11 @@ int main(void)
   string_replace_at(s1, 6, 3, "World");
   assert(string_equal_str_p(s1, "HELLO World!"));
 
+  h = string_pbrk(s1, "AB");
+  assert(h==STRING_FAILURE);
+  h = string_pbrk(s1, "oO");
+  assert(h==4);
+
   string_clear (s1);
   string_clear (s2);