diff --git a/Makefile b/Makefile
index bcd9af7..4c3ea00 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
-example: main.c
-	cc main.c -o example
+example: main.c foo.c
+	cc main.c foo.c -o example
 
 .PHONY: clean
 
diff --git a/foo.c b/foo.c
new file mode 100644
index 0000000..6c59816
--- /dev/null
+++ b/foo.c
@@ -0,0 +1,7 @@
+#include "foo.h"
+
+#include <stdio.h>
+
+void foo(void) {
+	puts("Hello World from foo().");
+}
diff --git a/foo.h b/foo.h
new file mode 100644
index 0000000..c42d22b
--- /dev/null
+++ b/foo.h
@@ -0,0 +1,6 @@
+#ifndef FOO_H
+#define FOO_H
+
+void foo(void);
+
+#endif
diff --git a/main.c b/main.c
index e1ea961..7de1619 100644
--- a/main.c
+++ b/main.c
@@ -1,7 +1,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "foo.h"
+
 int main(void) {
 	puts("Hello World");
+	foo();
 	return EXIT_SUCCESS;
 }