diff --git a/configure b/configure
index 59c17a54f..8ef5da87b 100755
--- a/configure
+++ b/configure
@@ -6435,7 +6435,7 @@ fi
 rm -f conftest.l $LEX_OUTPUT_ROOT.c
 
 fi
-if test "$LEX" != ""; then
+if test "$LEX" != "" -a "$LEX" != ":"; then
 
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for yylex_destroy" >&5
 $as_echo_n "checking for yylex_destroy... " >&6; }
@@ -6459,7 +6459,7 @@ EOF
 $as_echo "yes" >&6; }
 	else { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; };
-		LEX=""
+		LEX=":"
 	fi
 
 fi
diff --git a/configure.ac b/configure.ac
index 875bbc69d..5888a05b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -335,12 +335,12 @@ AC_DEFUN([ACX_YYLEX_OPTION], [
 EOF
 		AC_MSG_RESULT(yes)
 	else AC_MSG_RESULT(no);
-		LEX=""
+		LEX=":"
 	fi
 ])
 
 AC_PROG_LEX
-if test "$LEX" != ""; then
+if test "$LEX" != "" -a "$LEX" != ":"; then
 ACX_YYLEX_DESTROY
 ACX_YYLEX_OPTION
 fi