diff --git a/src/ffi.rs b/src/ffi.rs
index a7633b5..3cdffa3 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -16,9 +16,11 @@
 //! # FFI bindings
 //! Direct bindings to the underlying C library functions. These should
 //! not be needed for most users.
-use std::mem;
-use std::hash;
-use std::os::raw::{c_int, c_uchar, c_uint, c_void};
+use core::{mem, hash};
+use core::ffi::c_void;
+use crate::types::*;
+// use std::os::raw::{c_int, c_uchar, c_uint, c_void};
+
 
 /// Flag for context to enable no precomputation
 pub const SECP256K1_START_NONE: c_uint = 1;
diff --git a/src/lib.rs b/src/lib.rs
index 89c61f8..52a4e13 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -147,6 +147,7 @@ use core::{fmt, ptr, str};
 
 #[macro_use]
 mod macros;
+mod types;
 pub mod constants;
 pub mod ecdh;
 pub mod ffi;
diff --git a/src/types.rs b/src/types.rs
new file mode 100644
index 0000000..9bcb3b9
--- /dev/null
+++ b/src/types.rs
@@ -0,0 +1,5 @@
+#![allow(non_camel_case_types)]
+pub type c_int = i32;
+pub type c_uchar = u8;
+pub type c_uint = u32;
+pub use core::ffi::c_void;
\ No newline at end of file