diff --git a/src/unix/redox/mod.rs b/src/unix/redox/mod.rs
index 3bb7b044d0c1b..e6dcf540cfb7d 100644
--- a/src/unix/redox/mod.rs
+++ b/src/unix/redox/mod.rs
@@ -1,5 +1,11 @@
 pub type c_char = i8;
+#[cfg(target_pointer_width = "32")]
+pub type c_long = i32;
+#[cfg(target_pointer_width = "32")]
+pub type c_ulong = u32;
+#[cfg(target_pointer_width = "64")]
 pub type c_long = i64;
+#[cfg(target_pointer_width = "64")]
 pub type c_ulong = u64;
 pub type wchar_t = i32;