diff --git a/src/util/system.cpp b/src/util/system.cpp
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -1296,14 +1296,14 @@
     }
 #endif
 // On most POSIX systems (e.g. Linux, but not BSD) the environment's locale may
-// be invalid, in which case the "C" locale is used as fallback.
+// be invalid, in which case the "C.UTF-8" locale is used as fallback.
 #if !defined(WIN32) && !defined(MAC_OSX) && !defined(__FreeBSD__) &&           \
     !defined(__OpenBSD__)
     try {
         // Raises a runtime error if current locale is invalid.
         std::locale("");
     } catch (const std::runtime_error &) {
-        setenv("LC_ALL", "C", 1);
+        setenv("LC_ALL", "C.UTF-8", 1);
     }
 #elif defined(WIN32)
     // Set the default input/output charset is utf-8