diff --git a/src/common.rs b/src/common.rs
index 1bbf55073..b74ef3d16 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -1126,11 +1126,10 @@ pub fn str2wcstring(inp: &[u8]) -> WString {
             // TODO This check used to be conditionally compiled only on affected platforms.
             true
         } else {
-            const _: () = assert!(mem::size_of::<libc::wchar_t>() == mem::size_of::<char>());
             let mut codepoint = u32::from(c);
             ret = unsafe {
                 mbrtowc(
-                    std::ptr::addr_of_mut!(codepoint).cast(),
+                    std::ptr::addr_of_mut!(codepoint),
                     std::ptr::addr_of!(inp[pos]).cast(),
                     inp.len() - pos,
                     &mut state,
@@ -1333,9 +1332,7 @@ macro_rules! LL {
 fn can_be_encoded(wc: char) -> bool {
     let mut converted = [0 as libc::c_char; AT_LEAST_MB_LEN_MAX];
     let mut state = zero_mbstate();
-    unsafe {
-        wcrtomb(converted.as_mut_ptr(), wc as libc::wchar_t, &mut state) != 0_usize.wrapping_sub(1)
-    }
+    unsafe { wcrtomb(converted.as_mut_ptr(), wc as u32, &mut state) != 0_usize.wrapping_sub(1) }
 }
 
 /// Call read, blocking and repeating on EINTR. Exits on EAGAIN.
diff --git a/src/input_common.rs b/src/input_common.rs
index caeecc681..5f154a061 100644
--- a/src/input_common.rs
+++ b/src/input_common.rs
@@ -898,7 +898,7 @@ fn parse_codepoint(
         let mut codepoint = u32::from(res);
         let sz = unsafe {
             mbrtowc(
-                std::ptr::addr_of_mut!(codepoint).cast(),
+                std::ptr::addr_of_mut!(codepoint),
                 std::ptr::addr_of!(read_byte).cast(),
                 1,
                 state,
diff --git a/src/tests/string_escape.rs b/src/tests/string_escape.rs
index 4428d679c..88a0a607d 100644
--- a/src/tests/string_escape.rs
+++ b/src/tests/string_escape.rs
@@ -246,7 +246,7 @@ fn test_convert_private_use() {
         let len = unsafe {
             wcrtomb(
                 std::ptr::addr_of_mut!(converted[0]).cast(),
-                c as libc::wchar_t,
+                c as u32,
                 &mut state,
             )
         };
diff --git a/src/wcstringutil.rs b/src/wcstringutil.rs
index ab220a073..352d7381c 100644
--- a/src/wcstringutil.rs
+++ b/src/wcstringutil.rs
@@ -331,7 +331,7 @@ pub fn wcs2string_callback(input: &wstr, mut func: impl FnMut(&[u8]) -> bool) ->
             let len = unsafe {
                 wcrtomb(
                     std::ptr::addr_of_mut!(converted[0]).cast(),
-                    c as libc::wchar_t,
+                    c as u32,
                     &mut state,
                 )
             };
diff --git a/src/wutil/encoding.rs b/src/wutil/encoding.rs
index a3661661e..66384ae12 100644
--- a/src/wutil/encoding.rs
+++ b/src/wutil/encoding.rs
@@ -1,11 +1,8 @@
 extern "C" {
-    pub fn wcrtomb(s: *mut libc::c_char, wc: libc::wchar_t, ps: *mut mbstate_t) -> usize;
-    pub fn mbrtowc(
-        pwc: *mut libc::wchar_t,
-        s: *const libc::c_char,
-        n: usize,
-        p: *mut mbstate_t,
-    ) -> usize;
+    #[cfg_attr(target_os = "cygwin", link_name = "c32rtomb")]
+    pub fn wcrtomb(s: *mut libc::c_char, wc: u32, ps: *mut mbstate_t) -> usize;
+    #[cfg_attr(target_os = "cygwin", link_name = "mbrtoc32")]
+    pub fn mbrtowc(pwc: *mut u32, s: *const libc::c_char, n: usize, p: *mut mbstate_t) -> usize;
 }
 
 // HACK This should be mbstate_t from libc but that's not exposed.  Since it's only written by