diff --git a/include/fmt/format.cc b/include/fmt/format.cc
index 429657fb..6da96f71 100644
--- a/include/fmt/format.cc
+++ b/include/fmt/format.cc
@@ -280,9 +280,16 @@ const uint64_t internal::basic_data<T>::POWERS_OF_10_64[] = {
 
 FMT_FUNC internal::utf8_to_utf16::utf8_to_utf16(string_view s) {
   static const char ERROR_MSG[] = "cannot convert string from UTF-8 to UTF-16";
-  if (s.size() > INT_MAX)
+  if (s.size() > INT_MAX || s.data() == nullptr)
     FMT_THROW(windows_error(ERROR_INVALID_PARAMETER, ERROR_MSG));
   int s_size = static_cast<int>(s.size());
+  if (s_size == 0) // MultiByteToWideChar does not support zero length, handle separately
+  {
+      buffer_.resize(1);
+      buffer_[0] = 0;
+      return;
+  }
+
   int length = MultiByteToWideChar(
       CP_UTF8, MB_ERR_INVALID_CHARS, s.data(), s_size, FMT_NULL, 0);
   if (length == 0)
@@ -303,9 +310,16 @@ FMT_FUNC internal::utf16_to_utf8::utf16_to_utf8(wstring_view s) {
 }
 
 FMT_FUNC int internal::utf16_to_utf8::convert(wstring_view s) {
-  if (s.size() > INT_MAX)
+  if (s.size() > INT_MAX || s.data() == nullptr)
     return ERROR_INVALID_PARAMETER;
   int s_size = static_cast<int>(s.size());
+  if (s_size == 0) // MultiByteToWideChar does not support zero length, handle separately
+  {
+      buffer_.resize(1);
+      buffer_[0] = 0;
+      return 0;
+  }
+
   int length = WideCharToMultiByte(
         CP_UTF8, 0, s.data(), s_size, FMT_NULL, 0, FMT_NULL, FMT_NULL);
   if (length == 0)
diff --git a/test/util-test.cc b/test/util-test.cc
index 97dabfbb..c9db1ae1 100644
--- a/test/util-test.cc
+++ b/test/util-test.cc
@@ -665,6 +665,13 @@ TEST(UtilTest, UTF16ToUTF8) {
   EXPECT_EQ(s.size(), u.size());
 }
 
+TEST(UtilTest, UTF16ToUTF8EmptyString) {
+	std::string s = "";
+	fmt::internal::UTF16ToUTF8 u(L"");
+	EXPECT_EQ(s, u.str());
+	EXPECT_EQ(s.size(), u.size());
+}
+
 TEST(UtilTest, UTF8ToUTF16) {
   std::string s = "лошадка";
   fmt::internal::utf8_to_utf16 u(s.c_str());
@@ -672,6 +679,13 @@ TEST(UtilTest, UTF8ToUTF16) {
   EXPECT_EQ(7, u.size());
 }
 
+TEST(UtilTest, UTF8ToUTF16EmptyString) {
+	std::string s = "";
+	fmt::internal::UTF8ToUTF16 u(s.c_str());
+	EXPECT_EQ(L"", u.str());
+	EXPECT_EQ(s.size(), u.size());
+}
+
 template <typename Converter, typename Char>
 void check_utf_conversion_error(
         const char *message,