diff --git a/dev/a11y_assessments/windows/runner/utils.cpp b/dev/a11y_assessments/windows/runner/utils.cpp
index f677d8d5f7..02f4362740 100644
--- a/dev/a11y_assessments/windows/runner/utils.cpp
+++ b/dev/a11y_assessments/windows/runner/utils.cpp
@@ -49,13 +49,13 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/dev/benchmarks/complex_layout/windows/runner/utils.cpp b/dev/benchmarks/complex_layout/windows/runner/utils.cpp
index b849ce2c32..6abcd65042 100644
--- a/dev/benchmarks/complex_layout/windows/runner/utils.cpp
+++ b/dev/benchmarks/complex_layout/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/dev/integration_tests/flutter_gallery/windows/runner/utils.cpp b/dev/integration_tests/flutter_gallery/windows/runner/utils.cpp
index f677d8d5f7..02f4362740 100644
--- a/dev/integration_tests/flutter_gallery/windows/runner/utils.cpp
+++ b/dev/integration_tests/flutter_gallery/windows/runner/utils.cpp
@@ -49,13 +49,13 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/dev/integration_tests/ui/windows/runner/utils.cpp b/dev/integration_tests/ui/windows/runner/utils.cpp
index f677d8d5f7..02f4362740 100644
--- a/dev/integration_tests/ui/windows/runner/utils.cpp
+++ b/dev/integration_tests/ui/windows/runner/utils.cpp
@@ -49,13 +49,13 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/dev/integration_tests/windows_startup_test/windows/runner/utils.cpp b/dev/integration_tests/windows_startup_test/windows/runner/utils.cpp
index f677d8d5f7..02f4362740 100644
--- a/dev/integration_tests/windows_startup_test/windows/runner/utils.cpp
+++ b/dev/integration_tests/windows_startup_test/windows/runner/utils.cpp
@@ -49,13 +49,13 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/dev/manual_tests/windows/runner/utils.cpp b/dev/manual_tests/windows/runner/utils.cpp
index b849ce2c32..6abcd65042 100644
--- a/dev/manual_tests/windows/runner/utils.cpp
+++ b/dev/manual_tests/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/examples/api/windows/runner/utils.cpp b/examples/api/windows/runner/utils.cpp
index b849ce2c32..6abcd65042 100644
--- a/examples/api/windows/runner/utils.cpp
+++ b/examples/api/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/examples/flutter_view/windows/runner/utils.cpp b/examples/flutter_view/windows/runner/utils.cpp
index b849ce2c32..6abcd65042 100644
--- a/examples/flutter_view/windows/runner/utils.cpp
+++ b/examples/flutter_view/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/examples/hello_world/windows/runner/utils.cpp b/examples/hello_world/windows/runner/utils.cpp
index b849ce2c32..6abcd65042 100644
--- a/examples/hello_world/windows/runner/utils.cpp
+++ b/examples/hello_world/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/examples/layers/windows/runner/utils.cpp b/examples/layers/windows/runner/utils.cpp
index f677d8d5f7..02f4362740 100644
--- a/examples/layers/windows/runner/utils.cpp
+++ b/examples/layers/windows/runner/utils.cpp
@@ -49,13 +49,13 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/examples/platform_channel/windows/runner/utils.cpp b/examples/platform_channel/windows/runner/utils.cpp
index a05ed58ca9..d9ca4c32c9 100644
--- a/examples/platform_channel/windows/runner/utils.cpp
+++ b/examples/platform_channel/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/examples/platform_view/windows/runner/utils.cpp b/examples/platform_view/windows/runner/utils.cpp
index b849ce2c32..6abcd65042 100644
--- a/examples/platform_view/windows/runner/utils.cpp
+++ b/examples/platform_view/windows/runner/utils.cpp
@@ -49,12 +49,12 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
diff --git a/packages/flutter_tools/templates/app_shared/windows.tmpl/runner/utils.cpp b/packages/flutter_tools/templates/app_shared/windows.tmpl/runner/utils.cpp
index b2b08734db..3a0b46511a 100644
--- a/packages/flutter_tools/templates/app_shared/windows.tmpl/runner/utils.cpp
+++ b/packages/flutter_tools/templates/app_shared/windows.tmpl/runner/utils.cpp
@@ -45,13 +45,13 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length = ::WideCharToMultiByte(
+  unsigned int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
       -1, nullptr, 0, nullptr, nullptr)
     -1; // remove the trailing null character
   int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length <= 0 || target_length > utf8_string.max_size()) {
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);