diff --git a/Makefile.in b/Makefile.in
index 4d87b04f0..dba2617a8 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -248,7 +248,7 @@ syn-rules.cc: $(srcdir)/syn-rules.y
 	$(YACC) --verbose -p syn_ -o syn-rules.cc $(srcdir)/syn-rules.y
 
 lexor.cc: $(srcdir)/lexor.lex
-	$(LEX) -PVL -s -olexor.cc $(srcdir)/lexor.lex
+	$(LEX) -s -olexor.cc $(srcdir)/lexor.lex
 
 lexor_keyword.o: lexor_keyword.cc parse.h
 
diff --git a/driver/Makefile.in b/driver/Makefile.in
index f31d76037..7a1930bb9 100644
--- a/driver/Makefile.in
+++ b/driver/Makefile.in
@@ -80,7 +80,7 @@ iverilog@EXEEXT@: $O
 	$(CC) $(LDFLAGS) $O -o iverilog@EXEEXT@ @EXTRALIBS@
 
 cflexor.c: cflexor.lex
-	$(LEX) -s -Pcf -ocflexor.c $(srcdir)/cflexor.lex
+	$(LEX) -s -ocflexor.c $(srcdir)/cflexor.lex
 
 cfparse.h cfparse.c: cfparse.y
 	$(YACC) --verbose -t -d -o cfparse.c --name-prefix=cf $(srcdir)/cfparse.y
diff --git a/driver/cflexor.lex b/driver/cflexor.lex
index 98dc9d0c2..770faa742 100644
--- a/driver/cflexor.lex
+++ b/driver/cflexor.lex
@@ -1,4 +1,4 @@
-
+%option prefix="cf"
 %option nounput
 %option noinput
 
diff --git a/ivlpp/lexor.lex b/ivlpp/lexor.lex
index 313011ada..ecb67d4f4 100644
--- a/ivlpp/lexor.lex
+++ b/ivlpp/lexor.lex
@@ -1,3 +1,4 @@
+%option prefix="yy"
 %{
 /*
  * Copyright (c) 1999-2010 Stephen Williams (steve@icarus.com)
diff --git a/lexor.lex b/lexor.lex
index f254245ac..ce3916746 100644
--- a/lexor.lex
+++ b/lexor.lex
@@ -1,4 +1,4 @@
-
+%option prefix="VL"
 %option never-interactive
 %option nounput
 
diff --git a/vhdlpp/lexor.lex b/vhdlpp/lexor.lex
index 831a3d82a..4aa64c19b 100644
--- a/vhdlpp/lexor.lex
+++ b/vhdlpp/lexor.lex
@@ -1,4 +1,4 @@
-
+%option prefix="yy"
 %option never-interactive
 %option nounput
 
diff --git a/vpi/Makefile.in b/vpi/Makefile.in
index f7d9ad8ed..717aeeebf 100644
--- a/vpi/Makefile.in
+++ b/vpi/Makefile.in
@@ -121,12 +121,12 @@ system.vpi: $O $(OPP) ../vvp/libvpi.a
 	$(CXX) @shared@ -o $@ $O $(OPP) -L../vvp $(LDFLAGS) -lvpi $(SYSTEM_VPI_LDFLAGS)
 
 sys_readmem_lex.c: sys_readmem_lex.lex
-	$(LEX) -t -Preadmem $(srcdir)/sys_readmem_lex.lex > sys_readmem_lex.c
+	$(LEX) -t $(srcdir)/sys_readmem_lex.lex > sys_readmem_lex.c
 
 sdf_lexor.o: sdf_lexor.c sdf_parse.h
 
 sdf_lexor.c: sdf_lexor.lex
-	$(LEX) -t -Psdf $(srcdir)/sdf_lexor.lex > sdf_lexor.c
+	$(LEX) -t $(srcdir)/sdf_lexor.lex > sdf_lexor.c
 
 sdf_parse.c sdf_parse.h: $(srcdir)/sdf_parse.y
 	$(YACC) --verbose -d -p sdf -o sdf_parse.c $(srcdir)/sdf_parse.y
@@ -134,7 +134,7 @@ sdf_parse.c sdf_parse.h: $(srcdir)/sdf_parse.y
 table_mod_lexor.o: table_mod_lexor.c table_mod_parse.h
 
 table_mod_lexor.c: $(srcdir)/table_mod_lexor.lex
-	$(LEX) -t -Ptblmod $< > $@
+	$(LEX) -t $< > $@
 
 table_mod_parse.c table_mod_parse.h: $(srcdir)/table_mod_parse.y
 	$(YACC) --verbose -d -p tblmod -o table_mod_parse.c $<
diff --git a/vpi/sdf_lexor.lex b/vpi/sdf_lexor.lex
index 8c9c5b591..0a1210dbb 100644
--- a/vpi/sdf_lexor.lex
+++ b/vpi/sdf_lexor.lex
@@ -1,4 +1,4 @@
-
+%option prefix="sdf"
 %option never-interactive
 %option nounput
 %option noinput
diff --git a/vpi/sys_readmem_lex.lex b/vpi/sys_readmem_lex.lex
index 9454b2cfb..6cf029c04 100644
--- a/vpi/sys_readmem_lex.lex
+++ b/vpi/sys_readmem_lex.lex
@@ -1,4 +1,4 @@
-
+%option prefix="readmem"
 %option nounput
 %option noinput
 
diff --git a/vpi/table_mod_lexor.lex b/vpi/table_mod_lexor.lex
index 48be0587f..12958efff 100644
--- a/vpi/table_mod_lexor.lex
+++ b/vpi/table_mod_lexor.lex
@@ -1,4 +1,4 @@
-
+%option prefix="tblmod"
 %option never-interactive
 %option noinput
 %option nounput
diff --git a/vvp/lexor.lex b/vvp/lexor.lex
index 5fe395dea..6ea6745e5 100644
--- a/vvp/lexor.lex
+++ b/vvp/lexor.lex
@@ -1,4 +1,4 @@
-
+%option prefix="yy"
 %option never-interactive
 %option nounput