prevent segfault

diff --git a/useful_functions.c b/useful_functions.c
index e0b1e4c..a36062e 100644 (file)
--- a/useful_functions.c
+++ b/useful_functions.c
@@ -151,6 +151,8 @@ int ebt_invert = 0;
  */
 int ebt_check_inverse(const char option[])
 {
+       if (!option)
+               return ebt_invert;
        if (strcmp(option, "!") == 0) {
                if (ebt_invert == 1)
                        ebt_print_error("double use of '!' not allowed");