diff --git a/crypto/authenc.c b/crypto/authenc.c
index 5ef7ba6..d0583a4 100644
--- a/crypto/authenc.c
+++ b/crypto/authenc.c
@@ -336,7 +336,7 @@
 		cryptlen += ivsize;
 	}
 
-	if (sg_is_last(assoc)) {
+	if (req->assoclen && sg_is_last(assoc)) {
 		authenc_ahash_fn = crypto_authenc_ahash;
 		sg_init_table(asg, 2);
 		sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);
@@ -490,7 +490,7 @@
 		cryptlen += ivsize;
 	}
 
-	if (sg_is_last(assoc)) {
+	if (req->assoclen && sg_is_last(assoc)) {
 		authenc_ahash_fn = crypto_authenc_ahash;
 		sg_init_table(asg, 2);
 		sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);