diff --git a/winpr/include/winpr/tchar.h b/winpr/include/winpr/tchar.h
index 80110436b..51283522f 100644
--- a/winpr/include/winpr/tchar.h
+++ b/winpr/include/winpr/tchar.h
@@ -37,6 +37,7 @@ typedef CHAR TCHAR;
 
 #ifdef UNICODE
 #define _tprintf wprintf
+#define _sntprintf snwprintf
 #define _tcslen _wcslen
 #define _tcsdup _wcsdup
 #define _tcscmp wcscmp
@@ -50,6 +51,7 @@ typedef CHAR TCHAR;
 #define _tcsnccmp wcsncmp
 #else
 #define _tprintf printf
+#define _sntprintf snprintf
 #define _tcslen strlen
 #define _tcsdup _strdup
 #define _tcscmp strcmp
diff --git a/winpr/libwinpr/environment/test/TestEnvironmentGetEnvironmentStrings.c b/winpr/libwinpr/environment/test/TestEnvironmentGetEnvironmentStrings.c
index cb0c5903a..6af6a410a 100644
--- a/winpr/libwinpr/environment/test/TestEnvironmentGetEnvironmentStrings.c
+++ b/winpr/libwinpr/environment/test/TestEnvironmentGetEnvironmentStrings.c
@@ -16,16 +16,22 @@ int TestEnvironmentGetEnvironmentStrings(int argc, char* argv[])
 
 	lpszEnvironmentBlock = GetEnvironmentStrings();
 
-	p = (TCHAR*)lpszEnvironmentBlock;
+	p = lpszEnvironmentBlock;
 
 	while (p[0] && p[1])
 	{
-		const int rc = _tprintf(_T("%s\n"), p);
+		const int rc = _sntprintf(NULL, 0, _T("%s\n"), p);
 		if (rc < 1)
+		{
+			_tprintf(_T("test failed: return %d\n"), rc);
 			goto fail;
+		}
 		length = _tcslen(p);
 		if (length != (size_t)(rc - 1))
+		{
+			_tprintf(_T("test failed: length %") _T(PRIuz) _T(" != %d [%s]\n"), length, rc - 1, p);
 			goto fail;
+		}
 		p += (length + 1);
 	}