diff -ru captagent-6.1.0.20/configure.ac captagent-6.1.0.20.alpine/configure.ac
--- captagent-6.1.0.20/configure.ac	2016-06-01 14:42:19.000000000 +0300
+++ captagent-6.1.0.20.alpine/configure.ac	2017-02-03 22:06:46.098797592 +0200
@@ -181,7 +181,7 @@
 echo "        the LDFLAGS to set its proper path.";
 AC_MSG_ERROR([Fatal:  libjson not found.])])])
 
-AC_CHECK_LIB(fl, yywrap, [ FLEX_LIBS="-lfl" ] , [AC_MSG_ERROR([captagent requires but cannot find libfl])])
+FLEX_LIBS="-lfl"
 
 AC_SUBST(PTHREAD_LIBS)
 AC_SUBST(DL_LIBS)