diff --git a/library/pkcs5.c b/library/pkcs5.c
index 7564733..68cbfa7 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -176,7 +176,7 @@
      * The value of keylen from pkcs5_parse_pbkdf2_params() is ignored
      * since it is optional and we don't know if it was set or not
      */
-    keylen = cipher_info->key_length / 8;
+    keylen = cipher_info->key_bitlen / 8;
 
     if( enc_scheme_params.tag != MBEDTLS_ASN1_OCTET_STRING ||
         enc_scheme_params.len != cipher_info->iv_size )