diff --git a/src/tools/jam/Jambase b/src/tools/jam/Jambase
index 3b6e9a426f..93ca0064ee 100644
--- a/src/tools/jam/Jambase
+++ b/src/tools/jam/Jambase
@@ -378,6 +378,7 @@ else if $(OS) = BEOS && $(OSPLAT) = PPC
 	CHGRP		?= chgrp ;
 	CHOWN		?= chown ;
 	FORTRAN		?= "" ;
+	LEX			?= flex ;
 	LIBDIR		?= /boot/home/config/lib ;
 	LINK		?= mwld ;
 	LINKFLAGS	?= "" ;
@@ -398,6 +399,7 @@ else if $(OS) = BEOS
 	CHGRP		?= chgrp ;
 	CHOWN		?= chown ;
 	FORTRAN		?= "" ;
+	LEX			?= flex ;
 	LIBDIR		?= /boot/home/config/lib ;
 	LINK		?= gcc ;
 	MANDIR		?= /boot/home/config/man ;
diff --git a/src/tools/jam/jambase.c b/src/tools/jam/jambase.c
index fdf89867e0..23f7845316 100644
--- a/src/tools/jam/jambase.c
+++ b/src/tools/jam/jambase.c
@@ -197,6 +197,7 @@ char *jambase[] = {
 "CHGRP		?= chgrp ;\n",
 "CHOWN		?= chown ;\n",
 "FORTRAN		?= \"\" ;\n",
+"LEX			?= flex ;\n",
 "LIBDIR		?= /boot/home/config/lib ;\n",
 "LINK		?= mwld ;\n",
 "LINKFLAGS	?= \"\" ;\n",
@@ -217,6 +218,7 @@ char *jambase[] = {
 "CHGRP		?= chgrp ;\n",
 "CHOWN		?= chown ;\n",
 "FORTRAN		?= \"\" ;\n",
+"LEX			?= flex ;\n",
 "LIBDIR		?= /boot/home/config/lib ;\n",
 "LINK		?= gcc ;\n",
 "MANDIR		?= /boot/home/config/man ;\n",