diff --git a/boring/src/x509/mod.rs b/boring/src/x509/mod.rs
index 47d7c9c3..a3b3a044 100644
--- a/boring/src/x509/mod.rs
+++ b/boring/src/x509/mod.rs
@@ -896,13 +896,13 @@ impl X509NameBuilder {
     ) -> Result<(), ErrorStack> {
         unsafe {
             let field = CString::new(field).unwrap();
-            assert!(value.len() <= c_int::max_value() as usize);
+            assert!(value.len() <= ValueLen::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 ValueLen,
                 -1,
                 0,
             ))
@@ -943,13 +943,13 @@ impl X509NameBuilder {
         ty: Asn1Type,
     ) -> Result<(), ErrorStack> {
         unsafe {
-            assert!(value.len() <= c_int::max_value() as usize);
+            assert!(value.len() <= ValueLen::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 ValueLen,
                 -1,
                 0,
             ))