diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
index ec2ae9d53cc2fed78878b6b82e62c1cf38c202c3..7b5876b24e6b872bc73661ec63952a484b9427df 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -898,11 +898,8 @@ namespace __format
 	     _FormatContext&) const
 	{
 	  auto __ymd = _S_date(__t);
-	  basic_string<_CharT> __s;
-#if ! _GLIBCXX_USE_CXX11_ABI
-	  __s.reserve(11);
-#endif
-	  __s += std::format(_GLIBCXX_WIDEN("{:04d}-  -  "), (int)__ymd.year());
+	  auto __s = std::format(_GLIBCXX_WIDEN("{:04d}-  -  "),
+				 (int)__ymd.year());
 	  auto __sv = _S_two_digits((unsigned)__ymd.month());
 	  __s[__s.size() - 5] = __sv[0];
 	  __s[__s.size() - 4] = __sv[1];
@@ -1093,11 +1090,8 @@ namespace __format
 	  // %T Equivalent to %H:%M:%S
 	  auto __hms = _S_hms(__t);
 
-	  basic_string<_CharT> __s;
-#if ! _GLIBCXX_USE_CXX11_ABI
-	  __s.reserve(11);
-#endif
-	  __s = std::format(_GLIBCXX_WIDEN("{:02d}:00"), __hms.hours().count());
+	  auto __s = std::format(_GLIBCXX_WIDEN("{:02d}:00"),
+				 __hms.hours().count());
 	  auto __sv = _S_two_digits(__hms.minutes().count());
 	  __s[__s.size() - 2] = __sv[0];
 	  __s[__s.size() - 1] = __sv[1];