diff --git a/mercurial/cext/revlog.c b/mercurial/cext/revlog.c
--- a/mercurial/cext/revlog.c
+++ b/mercurial/cext/revlog.c
@@ -168,7 +168,7 @@ static const long entry_cl2_offset_rank 
 /* next free offset: 73 */
 
 static const char comp_mode_inline = 2;
-static const char rank_unknown = -1;
+static const int rank_unknown = -1;
 
 static void raise_revlog_error(void)
 {
diff --git a/rust/hg-core/src/lock.rs b/rust/hg-core/src/lock.rs
--- a/rust/hg-core/src/lock.rs
+++ b/rust/hg-core/src/lock.rs
@@ -145,7 +145,7 @@ lazy_static::lazy_static! {
 
         /// Same as https://github.com/python/cpython/blob/v3.10.0/Modules/socketmodule.c#L5414
         const BUFFER_SIZE: usize = 1024;
-        let mut buffer = [0_i8; BUFFER_SIZE];
+        let mut buffer = [0 as libc::c_char; BUFFER_SIZE];
         let hostname_bytes = unsafe {
             let result = libc::gethostname(buffer.as_mut_ptr(), BUFFER_SIZE);
             if result != 0 {