diff --git a/include/fmt/format.h b/include/fmt/format.h
index d1208844..fa76aa11 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2123,16 +2123,14 @@ template <typename OutputIt, typename UInt, typename Char>
 auto write_int(OutputIt out, UInt value, unsigned prefix,
                const format_specs<Char>& specs,
                const digit_grouping<Char>& grouping) -> OutputIt {
-  static_assert(std::is_same<uint64_or_128_t<UInt>, UInt>::value, "");
-  auto minimum = [](int a, int b) { return a < b ? a : b; };
+  static_assert(std::is_same<uint64_or_128_t<UInt>, UInt>::value, ""); 
   int num_digits = 0;
-  char digits[40]; 
-
+  auto buffer = memory_buffer();
   switch (specs.type) {
   case presentation_type::none:
   case presentation_type::dec: {
-    num_digits = minimum(count_digits(value), 40);
-    format_decimal(digits, value, num_digits);
+    num_digits = count_digits(value);
+    format_decimal<Char>(appender(buffer), value, num_digits);
     break;
   }
   case presentation_type::hex_lower:
@@ -2140,8 +2138,8 @@ auto write_int(OutputIt out, UInt value, unsigned prefix,
     bool upper = specs.type == presentation_type::hex_upper;
     if (specs.alt)
       prefix_append(prefix, unsigned(upper ? 'X' : 'x') << 8 | '0');
-    num_digits = minimum(count_digits<4>(value), 40);
-    format_uint<4>(digits, value, num_digits, upper);
+    num_digits = count_digits<4>(value);
+    format_uint<4,Char>(appender(buffer), value, num_digits, upper);
     break;
   }
   case presentation_type::bin_lower:
@@ -2149,17 +2147,17 @@ auto write_int(OutputIt out, UInt value, unsigned prefix,
     bool upper = specs.type == presentation_type::bin_upper;
     if (specs.alt)
       prefix_append(prefix, unsigned(upper ? 'B' : 'b') << 8 | '0');
-    num_digits = minimum(count_digits<1>(value), 40);
-    format_uint<1>(digits, value, num_digits);
+    num_digits = count_digits<1>(value);
+    format_uint<1,Char>(appender(buffer), value, num_digits);
     break;
   }
   case presentation_type::oct: {
-    num_digits = minimum(count_digits<3>(value), 40);
+    num_digits = count_digits<3>(value);
     // Octal prefix '0' is counted as a digit, so only add it if precision
     // is not greater than the number of digits.
     if (specs.alt && specs.precision <= num_digits && value != 0)
       prefix_append(prefix, '0');
-    format_uint<3>(digits, value, num_digits);
+    format_uint<3,Char>(appender(buffer), value, num_digits);
     break;
   }
   case presentation_type::chr:
@@ -2171,10 +2169,10 @@ auto write_int(OutputIt out, UInt value, unsigned prefix,
   unsigned size = (prefix != 0 ? prefix >> 24 : 0) + to_unsigned(num_digits) +
                               to_unsigned(grouping.count_separators(num_digits));
   return write_padded<align::right>(
-      out, specs, size, size, [=](reserve_iterator<OutputIt> it) {
+      out, specs, size, size, [&](reserve_iterator<OutputIt> it) {
         for (unsigned p = prefix & 0xffffff; p  != 0; p >>= 8)
           *it++ = static_cast<Char>(p & 0xff); 
-        return grouping.apply(it, string_view(digits, to_unsigned(num_digits)));
+        return grouping.apply(it, string_view(buffer.data(), buffer.size()));
       });
 }