diff --git a/objc/src/message/gnustep.rs b/objc/src/message/gnustep.rs
index e20b31595..5f9fca026 100644
--- a/objc/src/message/gnustep.rs
+++ b/objc/src/message/gnustep.rs
@@ -1,13 +1,8 @@
 use core::mem;
-use objc_sys::objc_super;
+use objc_sys::{objc_msg_lookup, objc_msg_lookup_super, objc_super};
 
 use super::{Encode, Message, MessageArguments, MessageError};
-use crate::runtime::{Class, Imp, Object, Sel};
-
-extern "C" {
-    fn objc_msg_lookup(receiver: *mut Object, op: Sel) -> Imp;
-    fn objc_msg_lookup_super(sup: *const objc_super, sel: Sel) -> Imp;
-}
+use crate::runtime::{Class, Object, Sel};
 
 pub unsafe fn send_unverified<T, A, R>(obj: *const T, sel: Sel, args: A) -> Result<R, MessageError>
 where
@@ -20,7 +15,7 @@ where
     }
 
     let receiver = obj as *mut T as *mut Object;
-    let msg_send_fn = objc_msg_lookup(receiver, sel);
+    let msg_send_fn = objc_msg_lookup(receiver as *mut _, sel.as_ptr() as *const _);
     objc_try!({ A::invoke(msg_send_fn, receiver, sel, args) })
 }
 
@@ -40,6 +35,6 @@ where
         receiver: receiver as *mut _,
         super_class: superclass as *const Class as *const _,
     };
-    let msg_send_fn = objc_msg_lookup_super(&sup, sel);
+    let msg_send_fn = objc_msg_lookup_super(&sup, sel.as_ptr() as *const _);
     objc_try!({ A::invoke(msg_send_fn, receiver, sel, args) })
 }
diff --git a/objc_sys/src/message.rs b/objc_sys/src/message.rs
index 7a690a455..f93429b19 100644
--- a/objc_sys/src/message.rs
+++ b/objc_sys/src/message.rs
@@ -18,6 +18,13 @@ pub struct objc_super {
     pub super_class: *const objc_class,
 }
 
+#[cfg(gnustep)]
+extern "C" {
+    pub fn objc_msg_lookup(receiver: *mut objc_object, sel: *const objc_selector) -> IMP;
+    pub fn objc_msg_lookup_super(super: *const objc_super, sel: *const objc_selector) -> IMP;
+    // objc_msg_lookup_sender
+}
+
 extern "C" {
     pub fn objc_msgSend();
     #[cfg(apple)]
diff --git a/objc_sys/src/tmp_gnustep.rs b/objc_sys/src/tmp_gnustep.rs
deleted file mode 100644
index 3971f47c7..000000000
--- a/objc_sys/src/tmp_gnustep.rs
+++ /dev/null
@@ -1,185 +0,0 @@
-/* automatically generated by rust-bindgen 0.59.1 */
-
-pub const OBJC_SMALL_OBJECT_MASK: u32 = 7;
-pub const OBJC_SMALL_OBJECT_SHIFT: u32 = 3;
-pub const OBJC_CAP_EXCEPTIONS: u32 = 0;
-pub const OBJC_CAP_SYNCRONIZE: u32 = 1;
-pub const OBJC_CAP_PROPERTIES: u32 = 2;
-pub const OBJC_CAP_PROPERTY_INTROSPECTION: u32 = 3;
-pub const OBJC_CAP_OPTIONAL_PROTOCOLS: u32 = 4;
-pub const OBJC_CAP_NONFRAGILE_IVARS: u32 = 5;
-pub const OBJC_CAP_TYPE_DEPENDENT_DISPATCH: u32 = 6;
-pub const OBJC_CAP_LOW_MEMORY: u32 = 7;
-pub const OBJC_DEVELOPER_MODE: u32 = 8;
-pub const OBJC_UNIFIED_EXCEPTION_MODEL: u32 = 9;
-pub const OBJC_CAP_REGISTERED_COMPATIBILITY_ALIASES: u32 = 10;
-pub const OBJC_CAP_ARC: u32 = 11;
-pub const OBJC_CAP_GARBAGE_COLLECTION: u32 = 12;
-pub const OBJC_CAP_ASSOCIATED_REFERENCES: u32 = 13;
-pub const OBJC_CAP_SMALL_OBJECTS: u32 = 14;
-pub const OBJC_CAP_PROTOTYPES: u32 = 15;
-pub const OBJC_ARC_AUTORELEASE_DEBUG: u32 = 16;
-pub const OBJC_CAP_TRACING: u32 = 17;
-#[repr(C)]
-#[derive(Debug, Copy, Clone)]
-pub struct objc_slot2 {
-    pub method: IMP,
-}
-extern "C" {
-    pub static mut objc_method_cache_version: u64;
-}
-#[repr(C)]
-#[derive(Debug, Copy, Clone)]
-pub struct objc_slot {
-    pub owner: Class,
-    pub cachedFor: Class,
-    pub types: *const ::std::os::raw::c_char,
-    pub version: ::std::os::raw::c_int,
-    pub method: IMP,
-    pub selector: SEL,
-}
-extern "C" {
-    pub fn objc_msg_lookup(arg1: id, arg2: SEL) -> IMP;
-}
-extern "C" {
-    pub fn objc_msg_lookup_super(arg1: *mut objc_super, arg2: SEL) -> IMP;
-}
-extern "C" {
-    pub fn objc_msg_lookup_sender(receiver: *mut id, selector: SEL, sender: id) -> *mut objc_slot;
-}
-extern "C" {
-    pub fn objc_get_slot(arg1: Class, arg2: SEL) -> *mut objc_slot;
-}
-extern "C" {
-    pub fn objc_get_slot2(arg1: Class, arg2: SEL, arg3: *mut u64) -> *mut objc_slot2;
-}
-extern "C" {
-    pub fn objc_slot_lookup_version(
-        receiver: *mut id,
-        selector: SEL,
-        arg1: *mut u64,
-    ) -> *mut objc_slot2;
-}
-extern "C" {
-    pub fn objc_msg_lookup2(receiver: *mut id, selector: SEL) -> IMP;
-}
-extern "C" {
-    pub fn objc_test_capability(x: ::std::os::raw::c_int) -> ::std::os::raw::c_int;
-}
-#[repr(C)]
-#[derive(Debug, Copy, Clone)]
-pub struct objc_category {
-    _unused: [u8; 0],
-}
-extern "C" {
-    pub static mut _objc_lookup_class:
-        ::std::option::Option<unsafe extern "C" fn(name: *const ::std::os::raw::c_char) -> Class>;
-}
-extern "C" {
-    pub static mut _objc_load_callback:
-        ::std::option::Option<unsafe extern "C" fn(cls: Class, category: *mut objc_category)>;
-}
-extern "C" {
-    pub static mut objc_proxy_lookup:
-        ::std::option::Option<unsafe extern "C" fn(receiver: id, op: SEL) -> id>;
-}
-extern "C" {
-    pub static mut __objc_msg_forward3:
-        ::std::option::Option<unsafe extern "C" fn(arg1: id, arg2: SEL) -> *mut objc_slot>;
-}
-extern "C" {
-    pub static mut __objc_msg_forward2:
-        ::std::option::Option<unsafe extern "C" fn(arg1: id, arg2: SEL) -> IMP>;
-}
-extern "C" {
-    pub static mut _objc_unexpected_exception:
-        ::std::option::Option<unsafe extern "C" fn(exception: id)>;
-}
-extern "C" {
-    pub static mut _objc_class_for_boxing_foreign_exception:
-        ::std::option::Option<unsafe extern "C" fn(exceptionClass: i64) -> Class>;
-}
-extern "C" {
-    pub static mut _objc_selector_type_mismatch2: ::std::option::Option<
-        unsafe extern "C" fn(cls: Class, selector: SEL, result: *mut objc_slot2) -> IMP,
-    >;
-}
-extern "C" {
-    pub static mut _objc_selector_type_mismatch: ::std::option::Option<
-        unsafe extern "C" fn(cls: Class, selector: SEL, result: *mut objc_slot) -> *mut objc_slot,
-    >;
-}
-extern "C" {
-    pub static mut _objc_weak_load: ::std::option::Option<unsafe extern "C" fn(object: id) -> id>;
-}
-pub type objc_tracing_hook = ::std::option::Option<
-    unsafe extern "C" fn(
-        arg1: id,
-        arg2: SEL,
-        arg3: IMP,
-        arg4: ::std::os::raw::c_int,
-        arg5: *mut ::std::os::raw::c_void,
-    ) -> IMP,
->;
-extern "C" {
-    pub fn objc_registerTracingHook(arg1: SEL, arg2: objc_tracing_hook) -> ::std::os::raw::c_int;
-}
-extern "C" {
-    pub fn objc_skip_type_qualifiers(
-        type_: *const ::std::os::raw::c_char,
-    ) -> *const ::std::os::raw::c_char;
-}
-extern "C" {
-    pub fn objc_skip_typespec(
-        type_: *const ::std::os::raw::c_char,
-    ) -> *const ::std::os::raw::c_char;
-}
-extern "C" {
-    pub fn objc_skip_argspec(type_: *const ::std::os::raw::c_char)
-        -> *const ::std::os::raw::c_char;
-}
-extern "C" {
-    pub fn objc_sizeof_type(type_: *const ::std::os::raw::c_char) -> usize;
-}
-extern "C" {
-    pub fn objc_alignof_type(type_: *const ::std::os::raw::c_char) -> usize;
-}
-extern "C" {
-    pub fn objc_aligned_size(type_: *const ::std::os::raw::c_char) -> usize;
-}
-extern "C" {
-    pub fn objc_promoted_size(type_: *const ::std::os::raw::c_char) -> usize;
-}
-extern "C" {
-    pub fn method_get_number_of_arguments(method: *mut objc_method) -> ::std::os::raw::c_uint;
-}
-extern "C" {
-    pub fn objc_get_type_qualifiers(type_: *const ::std::os::raw::c_char)
-        -> ::std::os::raw::c_uint;
-}
-#[repr(C)]
-#[derive(Debug, Copy, Clone)]
-pub struct objc_struct_layout {
-    pub original_type: *const ::std::os::raw::c_char,
-    pub type_: *const ::std::os::raw::c_char,
-    pub prev_type: *const ::std::os::raw::c_char,
-    pub record_size: ::std::os::raw::c_uint,
-    pub record_align: ::std::os::raw::c_uint,
-}
-extern "C" {
-    pub fn objc_layout_structure(
-        type_: *const ::std::os::raw::c_char,
-        layout: *mut objc_struct_layout,
-    );
-}
-extern "C" {
-    pub fn objc_layout_structure_next_member(layout: *mut objc_struct_layout) -> BOOL;
-}
-extern "C" {
-    pub fn objc_layout_structure_get_info(
-        layout: *mut objc_struct_layout,
-        offset: *mut ::std::os::raw::c_uint,
-        align: *mut ::std::os::raw::c_uint,
-        type_: *mut *const ::std::os::raw::c_char,
-    );
-}
diff --git a/objc_sys/src/various.rs b/objc_sys/src/various.rs
index 0c78da6bd..dfc882c80 100644
--- a/objc_sys/src/various.rs
+++ b/objc_sys/src/various.rs
@@ -91,4 +91,7 @@ extern "C" {
     // #[deprecated = "not recommended"]
     // #[cfg(apple)]
     // pub fn _objc_flush_caches
+
+    // #[cfg(gnustep)]
+    // objc_test_capability
 }