diff --git a/aws-lc-rs/src/cbb.rs b/aws-lc-rs/src/cbb.rs
index c48a71b45d6..bb4853ade7b 100644
--- a/aws-lc-rs/src/cbb.rs
+++ b/aws-lc-rs/src/cbb.rs
@@ -72,3 +72,41 @@ impl Drop for LcCBB<'_> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::LcCBB;
+    use aws_lc::CBB_add_asn1_bool;
+
+    #[test]
+    fn dynamic_buffer() {
+        let mut cbb = LcCBB::new(4);
+        assert_eq!(1, unsafe { CBB_add_asn1_bool(cbb.as_mut_ptr(), 1) });
+        let buffer = cbb.into_buffer::<'_, ()>().expect("be copied to buffer");
+        assert_eq!(buffer.as_ref(), &[1, 1, 255]);
+    }
+
+    #[test]
+    fn dynamic_buffer_grows() {
+        let mut cbb = LcCBB::new(1);
+        assert_eq!(1, unsafe { CBB_add_asn1_bool(cbb.as_mut_ptr(), 1) });
+        let buffer = cbb.into_buffer::<'_, ()>().expect("be copied to buffer");
+        assert_eq!(buffer.as_ref(), &[1, 1, 255]);
+    }
+
+    #[test]
+    fn fixed_buffer() {
+        let mut buffer = [0u8; 4];
+        let mut cbb = LcCBB::new_fixed(&mut buffer);
+        assert_eq!(1, unsafe { CBB_add_asn1_bool(cbb.as_mut_ptr(), 1) });
+        let out_len = cbb.finish().expect("cbb finishable");
+        assert_eq!(&buffer[..out_len], &[1, 1, 255]);
+    }
+
+    #[test]
+    fn fixed_buffer_no_growth() {
+        let mut buffer = [0u8; 1];
+        let mut cbb = LcCBB::new_fixed(&mut buffer);
+        assert_ne!(1, unsafe { CBB_add_asn1_bool(cbb.as_mut_ptr(), 1) });
+    }
+}
diff --git a/aws-lc-rs/src/rsa/key.rs b/aws-lc-rs/src/rsa/key.rs
index a60b8258df1..662e7bc59c5 100644
--- a/aws-lc-rs/src/rsa/key.rs
+++ b/aws-lc-rs/src/rsa/key.rs
@@ -22,7 +22,7 @@ use aws_lc::{
     EVP_DigestSignInit, EVP_PKEY_assign_RSA, EVP_PKEY_new, RSA_generate_key_ex,
     RSA_generate_key_fips, RSA_get0_e, RSA_get0_n, RSA_get0_p, RSA_get0_q, RSA_new,
     RSA_parse_private_key, RSA_parse_public_key, RSA_public_key_to_bytes, RSA_set0_key, RSA_size,
-    BIGNUM, EVP_PKEY, EVP_PKEY_CTX, RSA, RSA_F4,
+    BIGNUM, EVP_PKEY, EVP_PKEY_CTX, RSA,
 };
 
 use mirai_annotations::verify_unreachable;
@@ -620,6 +620,14 @@ mod tests {
     use super::{KeyPair, KeySize, PublicKeyComponents};
     use crate::encoding::AsDer;
 
+    #[test]
+    fn keysize_len() {
+        assert_eq!(KeySize::Rsa2048.len(), 256);
+        assert_eq!(KeySize::Rsa3072.len(), 384);
+        assert_eq!(KeySize::Rsa4096.len(), 512);
+        assert_eq!(KeySize::Rsa8192.len(), 1024);
+    }
+
     macro_rules! generate_encode_decode {
         ($name:ident, $size:expr) => {
             #[test]