doc: Fix a typo.
diff --git a/doc/mainpage.dox b/doc/mainpage.dox
index ad11e49..85eeddc 100644
--- a/doc/mainpage.dox
+++ b/doc/mainpage.dox
@@ -56,7 +56,7 @@
 #include <stdarg.h>
 #include <stddef.h>
 #include <setjmp.h>
-#include <cmockery.h>
+#include <cmocka.h>
 
 /* A test case that does nothing and succeeds. */
 static void null_test_success(void **state) {