diff --git a/src/common/aes.c b/src/common/aes.c
index 71250cd0c5..6179b16744 100644
--- a/src/common/aes.c
+++ b/src/common/aes.c
@@ -156,6 +156,9 @@ void
 aes_free_cipher(aes_cnt_cipher_t *cipher)
 {
   assert(cipher);
+#ifdef USE_OPENSSL_EVP
+  EVP_CIPHER_CTX_cleanup(&cipher->key);
+#endif
   memset(cipher, 0, sizeof(cipher));
   tor_free(cipher);
 }