diff --git a/library/pkcs7.c b/library/pkcs7.c
index c1446de..fc6dd33 100644
--- a/library/pkcs7.c
+++ b/library/pkcs7.c
@@ -353,6 +353,7 @@
         name_cur = name_cur->next;
         mbedtls_free( name_prv );
     }
+    signer->issuer.next = NULL;
 }
 
 /**