--- main.c
+++ main.c
@@ -1633,9 +1633,11 @@
 
 	if (!C_plus_plus && !reentrant) {
 		outn ("extern int yylineno;");
-		OUT_BEGIN_CODE ();
-		outn ("int yylineno = 1;");
-		OUT_END_CODE ();
+		if (do_yylineno) {
+			OUT_BEGIN_CODE ();
+			outn ("int yylineno = 1;");
+			OUT_END_CODE ();
+		}
 	}
 
 	if (C_plus_plus) {
--- flex.skl
+++ flex.skl
@@ -80,6 +80,16 @@
 m4preproc_define(`M4_GEN_PREFIX',
     ``m4_define(yy[[$1]], [[M4_YY_PREFIX[[$1]]m4_ifelse($'`#,0,,[[($'`@)]])]])'')
 
+%# don't use yylineno in non-reentrant scanners when %option yylineno not given
+m4_ifdef( [[M4_YY_REENTRANT]],,
+    [[m4_ifdef( [[M4_YY_USE_LINENO]],,
+        [[
+        m4_define( [[M4_YY_NO_GET_LINENO]], [[]])
+        m4_define( [[M4_YY_NO_SET_LINENO]], [[]])
+        ]])
+    ]]
+)
+
 %if-c++-only
     /* The c++ scanner is a mess. The FlexLexer.h header file relies on the
      * following macro. This is required in order to pass the c++-multiple-scanners