diff --git a/include/fmt/base.h b/include/fmt/base.h
index daf7e3fed29d..e0baae256347 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -800,7 +800,8 @@ class basic_specs {
   template <typename Char> constexpr auto fill_unit() const -> Char {
     using uchar = unsigned char;
     return static_cast<Char>(static_cast<uchar>(fill_data_[0]) |
-                             (static_cast<uchar>(fill_data_[1]) << 8));
+                             (static_cast<uchar>(fill_data_[1]) << 8) |
+                             (static_cast<uchar>(fill_data_[2]) << 16));
   }
 
   FMT_CONSTEXPR void set_fill(char c) {
@@ -816,6 +817,7 @@ class basic_specs {
       unsigned uchar = static_cast<detail::unsigned_char<Char>>(s[0]);
       fill_data_[0] = static_cast<char>(uchar);
       fill_data_[1] = static_cast<char>(uchar >> 8);
+      fill_data_[2] = static_cast<char>(uchar >> 16);
       return;
     }
     FMT_ASSERT(size <= max_fill_size, "invalid fill");
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 622c2750b2e3..054641b6c3bb 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -677,7 +677,8 @@ FMT_CONSTEXPR void for_each_codepoint(string_view s, F f) {
   auto num_chars_left = to_unsigned(s.data() + s.size() - p);
   if (num_chars_left == 0) return;
 
-  FMT_ASSERT(num_chars_left < block_size, "");
+  // Suppress bogus -Wstringop-overflow.
+  if (FMT_GCC_VERSION) num_chars_left &= 3;
   char buf[2 * block_size - 1] = {};
   copy<char>(p, p + num_chars_left, buf);
   const char* buf_ptr = buf;
diff --git a/test/xchar-test.cc b/test/xchar-test.cc
index 215b659ff1e2..0f91aa319e84 100644
--- a/test/xchar-test.cc
+++ b/test/xchar-test.cc
@@ -72,16 +72,17 @@ TEST(xchar_test, format_explicitly_convertible_to_wstring_view) {
 #endif
 
 TEST(xchar_test, format) {
-  EXPECT_EQ(L"42", fmt::format(L"{}", 42));
-  EXPECT_EQ(L"4.2", fmt::format(L"{}", 4.2));
-  EXPECT_EQ(L"abc", fmt::format(L"{}", L"abc"));
-  EXPECT_EQ(L"z", fmt::format(L"{}", L'z'));
+  EXPECT_EQ(fmt::format(L"{}", 42), L"42");
+  EXPECT_EQ(fmt::format(L"{}", 4.2), L"4.2");
+  EXPECT_EQ(fmt::format(L"{}", L"abc"), L"abc");
+  EXPECT_EQ(fmt::format(L"{}", L'z'), L"z");
   EXPECT_THROW(fmt::format(fmt::runtime(L"{:*\x343E}"), 42), fmt::format_error);
-  EXPECT_EQ(L"true", fmt::format(L"{}", true));
-  EXPECT_EQ(L"a", fmt::format(L"{0}", L'a'));
-  EXPECT_EQ(L"Cyrillic letter \x42e",
-            fmt::format(L"Cyrillic letter {}", L'\x42e'));
-  EXPECT_EQ(L"abc1", fmt::format(L"{}c{}", L"ab", 1));
+  EXPECT_EQ(fmt::format(L"{}", true), L"true");
+  EXPECT_EQ(fmt::format(L"{0}", L'a'), L"a");
+  EXPECT_EQ(fmt::format(L"Letter {}", L'\x40e'), L"Letter \x40e"); // Ў
+  if (sizeof(wchar_t) == 4)
+    EXPECT_EQ(fmt::format(fmt::runtime(L"{:𓀨>3}"), 42), L"𓀨42");
+  EXPECT_EQ(fmt::format(L"{}c{}", L"ab", 1), L"abc1");
 }
 
 TEST(xchar_test, is_formattable) {