4 files changed, 12 insertions, 5 deletions
diff --git a/src/init/types.h b/src/init/types.h
index d06d171..2c56484 100644
--- a/src/init/types.h
+++ b/src/init/types.h
@@ -1,2 +1,4 @@
 #pragma once
+
+#define TYPES_INCLUDED
 typedef char* user_ptr;
diff --git a/src/kernel/types.h b/src/kernel/types.h
index eb12f08..891e644 100644
--- a/src/kernel/types.h
+++ b/src/kernel/types.h
@@ -1,3 +1,5 @@
 #pragma once
 #include <stdint.h>
+
+#define TYPES_INCLUDED
 typedef uintptr_t user_ptr;
diff --git a/src/shared/syscalls.h b/src/shared/syscalls.h
index 7a1acaf..0222f37 100644
--- a/src/shared/syscalls.h
+++ b/src/shared/syscalls.h
@@ -1,8 +1,10 @@
-// requires the user_ptr type from kernel/types.h or init/types.h
-
 #pragma once
 #include <stddef.h>
 
+#ifndef TYPES_INCLUDED
+#  error "please include <kernel/types.h> or <init/types.h> before this file"
+#endif
+
 typedef int handle_t;
 
 enum {
diff --git a/src/shared/vfs.h b/src/shared/vfs.h
index d88c424..730a288 100644
--- a/src/shared/vfs.h
+++ b/src/shared/vfs.h
@@ -1,8 +1,9 @@
-// requires the user_ptr type from kernel/types.h or init/types.h
-// TODO add some macro magic which prints an error when it isn't defined
-
 #pragma once
 
+#ifndef TYPES_INCLUDED
+#  error "please include <kernel/types.h> or <init/types.h> before this file"
+#endif
+
 enum vfs_op_types {
 	VFSOP_OPEN,
 	VFSOP_WRITE,