diff --git a/du5/program.c b/du5/program.c
index b262aa9..1d934f9 100644
--- a/du5/program.c
+++ b/du5/program.c
@@ -43,7 +43,7 @@ int main()
         else
         {
             sscanf(line, " %127[^?]", question);
-            strcat(question, "");
+            strcat(question, "?");
         }
     }