diff --git a/src/post_modules/Nettle/cipher.cmod b/src/post_modules/Nettle/cipher.cmod
index 3417cadcf2b7d890667eac999b51df05afb4e87c..7706aadb3eed5b23112e99bc224979d8011075fc 100644
--- a/src/post_modules/Nettle/cipher.cmod
+++ b/src/post_modules/Nettle/cipher.cmod
@@ -3478,6 +3478,7 @@ PIKECLASS BlockCipher16
 	if (!pstr->len) {
 	  // Unlikely, but make sure that it is initialized.
 	  blockcipher16_ccm_init_mac_mask("digest");
+	  mac_mask = THIS->mac_mask;
 	}
 
 	if (THIS->ctr->crypt_state && THIS->ctr->crypt_state->crypt) {