--- flex-2.6.4/src/Makefile.in.orig	Thu Jan 23 23:27:22 2020
+++ flex-2.6.4/src/Makefile.in	Thu Jan 23 23:27:51 2020
@@ -350,7 +350,7 @@
 LTLIBINTL = @LTLIBINTL@
 LTLIBOBJS = @LTLIBOBJS@
 LT_SYS_LIBRARY_PATH = @LT_SYS_LIBRARY_PATH@
-M4 = @M4@
+M4 = /usr/local/bin/m4
 MAKEINFO = @MAKEINFO@
 MANIFEST_TOOL = @MANIFEST_TOOL@
 MKDIR_P = @MKDIR_P@
@@ -444,7 +444,7 @@
 top_srcdir = @top_srcdir@
 AM_YFLAGS = -d
 AM_CPPFLAGS = -DLOCALEDIR=\"$(localedir)\"
-m4 = @M4@
+m4 = /usr/local/bin/m4
 @ENABLE_LIBFL_TRUE@lib_LTLIBRARIES = libfl.la
 libfl_la_SOURCES = \
 	libmain.c \