diff --git a/src/include/loop.h b/src/include/loop.h
index 4543551..24b4c28 100644
--- a/src/include/loop.h
+++ b/src/include/loop.h
@@ -1,3 +1,6 @@
+#ifndef _MYSHELLIN_LOOP
+#define _MYSHELLIN_LOOP
 void remove_new_line(char *line);
 void print_input_line();
 void loop();
+#endif
diff --git a/src/include/user.h b/src/include/user.h
index b9b383a..0b4b055 100644
--- a/src/include/user.h
+++ b/src/include/user.h
@@ -1 +1,4 @@
+#ifndef _MYSHELLIN_USER
+#define _MYSHELLIN_USER
 char *get_user();
+#endif