diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 908999ab..d2e7ccbb 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -558,7 +558,13 @@ inline void write_digit2_separated(char* buf, unsigned a, unsigned b,
   auto usep = static_cast<unsigned long long>(sep);
   // Add ASCII '0' to each digit byte and insert separators.
   digits |= 0x3030003030003030 | (usep << 16) | (usep << 40);
-  memcpy(buf, &digits, 8);
+  if (is_big_endian()) {
+    char tmp[8];
+    memcpy(tmp, &digits, 8);
+    std::reverse_copy(tmp, tmp + 8, buf);
+  } else {
+    memcpy(buf, &digits, 8);
+  }
 }
 
 template <typename Period> FMT_CONSTEXPR inline const char* get_units() {