diff --git a/src/x509/mod.rs b/src/x509/mod.rs
index 45f2467..a03a8aa 100644
--- a/src/x509/mod.rs
+++ b/src/x509/mod.rs
@@ -893,13 +893,13 @@ impl X509NameBuilder {
     pub fn append_entry_by_text(&mut self, field: &str, value: &str) -> Result<(), ErrorStack> {
         unsafe {
             let field = CString::new(field).unwrap();
-            assert!(value.len() <= c_int::max_value() as usize);
+            assert!(value.len() <= isize::max_value() as usize);
             cvt(ffi::X509_NAME_add_entry_by_txt(
                 self.0.as_ptr(),
                 field.as_ptr() as *mut _,
                 ffi::MBSTRING_UTF8,
                 value.as_ptr(),
-                value.len() as c_int,
+                value.len() as isize,
                 -1,
                 0,
             ))
@@ -920,13 +920,13 @@ impl X509NameBuilder {
     ) -> Result<(), ErrorStack> {
         unsafe {
             let field = CString::new(field).unwrap();
-            assert!(value.len() <= c_int::max_value() as usize);
+            assert!(value.len() <= isize::max_value() as usize);
             cvt(ffi::X509_NAME_add_entry_by_txt(
                 self.0.as_ptr(),
                 field.as_ptr() as *mut _,
                 ty.as_raw(),
                 value.as_ptr(),
-                value.len() as c_int,
+                value.len() as isize,
                 -1,
                 0,
             ))
@@ -941,13 +941,13 @@ impl X509NameBuilder {
     /// [`X509_NAME_add_entry_by_NID`]: https://www.openssl.org/docs/man1.1.0/crypto/X509_NAME_add_entry_by_NID.html
     pub fn append_entry_by_nid(&mut self, field: Nid, value: &str) -> Result<(), ErrorStack> {
         unsafe {
-            assert!(value.len() <= c_int::max_value() as usize);
+            assert!(value.len() <= isize::max_value() as usize);
             cvt(ffi::X509_NAME_add_entry_by_NID(
                 self.0.as_ptr(),
                 field.as_raw(),
                 ffi::MBSTRING_UTF8,
                 value.as_ptr() as *mut _,
-                value.len() as c_int,
+                value.len() as isize,
                 -1,
                 0,
             ))
@@ -967,13 +967,13 @@ impl X509NameBuilder {
         ty: Asn1Type,
     ) -> Result<(), ErrorStack> {
         unsafe {
-            assert!(value.len() <= c_int::max_value() as usize);
+            assert!(value.len() <= isize::max_value() as usize);
             cvt(ffi::X509_NAME_add_entry_by_NID(
                 self.0.as_ptr(),
                 field.as_raw(),
                 ty.as_raw(),
                 value.as_ptr() as *mut _,
-                value.len() as c_int,
+                value.len() as isize,
                 -1,
                 0,
             ))