diff --git a/UnitTests/string.cpp b/UnitTests/string.cpp
index 10680c94a..ab2612c19 100644
--- a/UnitTests/string.cpp
+++ b/UnitTests/string.cpp
@@ -17,25 +17,26 @@ namespace UnitTests
 	public:
 		TEST_METHOD(sprintf)
 		{
-			Assert::AreEqual(L"This is a test.", stdex::sprintf(L"This is %ls.", stdex::locale_default, L"a test").c_str());
-			Assert::AreEqual<size_t>(15, stdex::sprintf(L"This is %ls.", stdex::locale_default, L"a test").size());
-			Assert::AreEqual("This is a test.", stdex::sprintf("This is %s.", stdex::locale_default, "a test").c_str());
-			Assert::AreEqual<size_t>(15, stdex::sprintf("This is %s.", stdex::locale_default, "a test").size());
+			stdex::locale locale(stdex::create_locale(LC_ALL, "en_US.UTF-8"));
 
-			// swprintf functions return EILSEQ when %ls inserts contain emoji on Mac. 😢
-			Assert::AreEqual(L"This is a tést.", stdex::sprintf(L"This is %ls.", stdex::locale_default, L"a tést").c_str());
-			Assert::AreEqual("This is a 🐔Test🐮.", stdex::sprintf("This is %s.", stdex::locale_default, "a 🐔Test🐮").c_str());
+			Assert::AreEqual(L"This is a test.", stdex::sprintf(L"This is %ls.", locale, L"a test").c_str());
+			Assert::AreEqual<size_t>(15, stdex::sprintf(L"This is %ls.", locale, L"a test").size());
+			Assert::AreEqual("This is a test.", stdex::sprintf("This is %s.", locale, "a test").c_str());
+			Assert::AreEqual<size_t>(15, stdex::sprintf("This is %s.", locale, "a test").size());
+
+			Assert::AreEqual(L"This is a 🐔Test🐮.", stdex::sprintf(L"This is %ls.", locale, L"a 🐔Test🐮").c_str());
+			Assert::AreEqual("This is a 🐔Test🐮.", stdex::sprintf("This is %s.", locale, "a 🐔Test🐮").c_str());
 
 			wstring wstr;
 			std::string str;
-			for (size_t i = 0; i < 2000; i++) {
-				wstr += L"tést\r\n";
+			for (size_t i = 0; i < 200; i++) {
+				wstr += L"🐔Test🐮\r\n";
 				str += "🐔Test🐮\r\n";
 			}
-			Assert::AreEqual(wstr.c_str(), stdex::sprintf(L"%ls", stdex::locale_default, wstr.data()).c_str());
-			Assert::AreEqual(wstr.size(), stdex::sprintf(L"%ls", stdex::locale_default, wstr.data()).size());
-			Assert::AreEqual(str.c_str(), stdex::sprintf("%s", stdex::locale_utf8, str.data()).c_str());
-			Assert::AreEqual(str.size(), stdex::sprintf("%s", stdex::locale_utf8, str.data()).size());
+			Assert::AreEqual(wstr.c_str(), stdex::sprintf(L"%ls", locale, wstr.data()).c_str());
+			Assert::AreEqual(wstr.size(), stdex::sprintf(L"%ls", locale, wstr.data()).size());
+			Assert::AreEqual(str.c_str(), stdex::sprintf("%s", locale, str.data()).c_str());
+			Assert::AreEqual(str.size(), stdex::sprintf("%s", locale, str.data()).size());
 		}
 	};
 }