diff --git a/include/fmt/format.h b/include/fmt/format.h
index 4a1663bb3e27..ed48a7c07be9 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -773,7 +773,8 @@ inline auto code_point_index(string_view s, size_t n) -> size_t {
   for (size_t i = 0, size = s.size(); i != size; ++i) {
     if ((data[i] & 0xc0) != 0x80 && ++num_code_points > n) return i;
   }
-  return s.size();
+  size_t size = s.size();
+  return n < size ? n : size;
 }
 
 inline auto code_point_index(basic_string_view<char8_type> s, size_t n)
diff --git a/test/xchar-test.cc b/test/xchar-test.cc
index 1deab2d02c9d..96fb4cfbea84 100644
--- a/test/xchar-test.cc
+++ b/test/xchar-test.cc
@@ -155,6 +155,8 @@ TEST(xchar_test, format_utf8_precision) {
   EXPECT_EQ(fmt::detail::compute_width(result), 4);
   EXPECT_EQ(result.size(), 5);
   EXPECT_EQ(from_u8str(result), from_u8str(str.substr(0, 5)));
+
+  EXPECT_EQ(fmt::format("{:.0}", "\xad").size(), 0);
 }
 
 TEST(xchar_test, format_to) {