diff --git a/exercises/os/fork_102.md b/exercises/os/fork_102.md
index 6ad5408..c41dd6d 100644
--- a/exercises/os/fork_102.md
+++ b/exercises/os/fork_102.md
@@ -4,13 +4,14 @@ Answer the questions given the following program (without running it):
 
 ```
 #include<stdio.h>
+#include <unistd.h> 
 
 int main()
 {
-fork();
-fork();
-printf("\nyay\n");
-return 0;
+  fork();
+  fork();
+  printf("\nyay\n");
+  return 0;
 }
 ```