diff --git a/src/flexfix b/src/flexfix
index 3a563c41e..652f80364 100755
--- a/src/flexfix
+++ b/src/flexfix
@@ -19,7 +19,7 @@ my $Opt_Prefix = $ARGV[0] or die "%Error: No prefix specified,";
 
 foreach my $line (<STDIN>) {
     # Fix flex 2.6.0 warning
-    $line =~ s/ > YY_CURRENT_BUFFER_LVALUE->yy_buf_size/ > (int) YY_CURRENT_BUFFER_LVALUE->yy_buf_size/;
+    $line =~ s/\(\(int\) \(\(yy_n_chars\) \+ number_to_move\) > YY_CURRENT_BUFFER_LVALUE->yy_buf_size\)/((int) ((yy_n_chars) + number_to_move) > (int) YY_CURRENT_BUFFER_LVALUE->yy_buf_size)/g;
     $line =~ s/ number_to_move == YY_MORE_ADJ / (int)number_to_move == (int)YY_MORE_ADJ /;
     # Fix flex 2.5.4 namespace omission
     $line =~ s/^class istream;/\#include <iostream>\nusing namespace std;\n/;