diff --git a/vpi/sdf_lexor.lex b/vpi/sdf_lexor.lex
index c4b03d3fe..f5b4d3a7d 100644
--- a/vpi/sdf_lexor.lex
+++ b/vpi/sdf_lexor.lex
@@ -50,12 +50,12 @@ static int yywrap(void)
 %%
 
   /* Skip C++-style comments. */
-"//".* { sdflloc.first_line += 1; }
+"//".* { ; }
 
   /* Skip C-style comments. */
 "/*"           { BEGIN(CCOMMENT); }
-<CCOMMENT>.    { yymore(); }
-<CCOMMENT>\n   { sdflloc.first_line += 1; yymore(); }
+<CCOMMENT>.    { ; }
+<CCOMMENT>\n   { sdflloc.first_line += 1; }
 <CCOMMENT>"*/" { BEGIN(0); }
 
 [ \m\t] { /* Skip white space. */; }