diff --git a/ex10.c b/ex10.c
index c06d77b..d0aed12 100644
--- a/ex10.c
+++ b/ex10.c
@@ -10,12 +10,13 @@ int main(int argc, char *argv[])
 
     char *states[] = {
         "California", "Oregon",
-        "Washington", "Texas"
+        "Washington", "Texas",
+        NULL
     };
-    int num_states = 4;
+    char *state = "";
 
-    for(i = 0; i < num_states; i++) {
-        printf("state %d: %s\n", i, states[i]);
+    for(i = 0; NULL != (state = states[i]); i++) {
+        printf("state %d: %s\n", i, state);
     }
 
     return 0;