diff --git a/include/fmt/format.h b/include/fmt/format.h
index 5149fd66..108307eb 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -553,7 +553,7 @@ FMT_CONSTEXPR auto fill_n(OutputIt out, Size count, const T& value)
 template <typename T, typename Size>
 FMT_CONSTEXPR20 auto fill_n(T* out, Size count, char value) -> T* {
   if (is_constant_evaluated()) return fill_n<T*, Size, T>(out, count, value);
-  std::memset(out, value, to_unsigned(count));
+  std::memset(out, value, to_unsigned(count) * sizeof(T));
   return out + count;
 }