The <iomanip> header is already checked; <iomanip.h> is pre-C++98 alias. --- id3lib-3.8.3/configure.in.old 2003-03-02 00:23:00.000000000 +0000 +++ id3lib-3.8.3/configure.in 2018-03-25 06:43:58.270837035 +0000 @@ -227,7 +227,6 @@ ) AC_CHECK_HEADERS( \ string \ - iomanip.h \ ,,AC_MSG_ERROR([Missing a vital header file for id3lib]) ) --- id3lib-3.8.3/configure.old 2003-03-02 00:23:00.000000000 +0000 +++ id3lib-3.8.3/configure 2018-03-25 06:44:02.260837054 +0000 @@ -10296,7 +10296,6 @@ for ac_header in \ string \ - iomanip.h \ do as_ac_Header=`echo "ac_cv_header_$ac_header" | $as_tr_sh`