diff --git a/openssl/src/ecdsa.rs b/openssl/src/ecdsa.rs
index 06be274f..8dfb742c 100644
--- a/openssl/src/ecdsa.rs
+++ b/openssl/src/ecdsa.rs
@@ -108,7 +108,7 @@ impl EcdsaSig {
         /// Decodes a DER-encoded ECDSA signature.
         ///
         /// This corresponds to [`d2i_ECDSA_SIG`].
-        /// 
+        ///
         /// [`d2i_ECDSA_SIG`]: https://www.openssl.org/docs/man1.1.0/crypto/d2i_ECDSA_SIG.html
         from_der,
         EcdsaSig,
@@ -121,7 +121,7 @@ impl EcdsaSigRef {
         /// Serializes the ECDSA signature into a DER-encoded ECDSASignature structure.
         ///
         /// This corresponds to [`i2d_ECDSA_SIG`].
-        /// 
+        ///
         /// [`i2d_ECDSA_SIG`]: https://www.openssl.org/docs/man1.1.0/crypto/i2d_ECDSA_SIG.html
         to_der,
         ffi::i2d_ECDSA_SIG
@@ -138,6 +138,11 @@ cfg_if! {
             r: *mut ffi::BIGNUM,
             s: *mut ffi::BIGNUM,
         ) -> c_int {
+            if r.is_null() || s.is_null() {
+                return 0;
+            }
+            ffi::BN_clear_free((*sig).r);
+            ffi::BN_clear_free((*sig).s);
             (*sig).r = r;
             (*sig).s = s;
             1