diff --git a/encoding.c b/encoding.c
index 38e28c8..c796a25 100644
--- a/encoding.c
+++ b/encoding.c
@@ -1212,16 +1212,19 @@ static int
 enc_set_filesystem_encoding(void)
 {
     int idx;
+
 #if defined NO_LOCALE_CHARMAP
     idx = rb_enc_to_index(rb_default_external_encoding());
+#elif defined(__APPLE__)
+    idx = rb_enc_find_index("UTF8-MAC");
 #elif defined _WIN32 || defined __CYGWIN__
     char cp[sizeof(int) * 8 / 3 + 4];
     snprintf(cp, sizeof cp, "CP%d", AreFileApisANSI() ? GetACP() : GetOEMCP());
     idx = rb_enc_find_index(cp);
-    if (idx < 0) idx = rb_ascii8bit_encindex();
 #else
     idx = rb_enc_to_index(rb_default_external_encoding());
 #endif
+    if (idx < 0) idx = rb_ascii8bit_encindex();
 
     enc_alias_internal("filesystem", idx);
     return idx;