diff --git a/src/Recipient.c b/src/Recipient.c
index da0543e..5a08b20 100644
--- a/src/Recipient.c
+++ b/src/Recipient.c
@@ -316,6 +316,7 @@
 		for (pRecip2 = pcose->m_recipientFirst; pRecip2 != NULL; pRecip2 = pRecip->m_recipientNext) {
 			if (_COSE_Recipient_decrypt(pRecip2, alg, cbitKeyX, pbKeyX, perr)) break;
 		}
+		CHECK_CONDITION(pRecip2 != NULL, COSE_ERR_NO_RECIPIENT_FOUND);
 	}
 
 	cnBody = _COSE_arrayget_int(&pcose->m_message, INDEX_BODY);
@@ -448,6 +449,7 @@
 	cn_Alg = _COSE_map_get_int(&pRecipient->m_encrypt.m_message, COSE_Header_Algorithm, COSE_BOTH, perr);
 	if (cn_Alg == NULL) goto errorReturn;
 
+	CHECK_CONDITION(cn_Alg->type != CN_CBOR_TEXT, COSE_ERR_UNKNOWN_ALGORITHM);
 	CHECK_CONDITION((cn_Alg->type == CN_CBOR_UINT) || (cn_Alg->type == CN_CBOR_INT), COSE_ERR_INVALID_PARAMETER);
 	alg = (int)cn_Alg->v.uint;
 
@@ -487,7 +489,7 @@
 		break;
 
 	default:
-		FAIL_CONDITION(COSE_ERR_INVALID_PARAMETER);
+		FAIL_CONDITION(COSE_ERR_UNKNOWN_ALGORITHM);
 	}
 
 	//  If we are doing direct encryption - then recipient generates the key
diff --git a/test/encrypt.c b/test/encrypt.c
index ea5b23a..b3b9ff5 100644
--- a/test/encrypt.c
+++ b/test/encrypt.c
@@ -176,7 +176,8 @@
 	cn_cbor * pSenderKey = cn_cbor_mapget_string(pRecipient, "sender_key");
 	if (pSenderKey != NULL) {
 		cn_cbor * pSendKey = BuildKey(pSenderKey, false);
-		if (!COSE_Recipient_SetSenderKey(hRecip, pSendKey, 2, NULL)) goto returnError;
+		cn_cbor * pKid = cn_cbor_mapget_string(pSenderKey, "kid");
+		if (!COSE_Recipient_SetSenderKey(hRecip, pSendKey, (pKid == NULL) ? 2 : 1, NULL)) goto returnError;
 	}
 
 	return hRecip;
@@ -636,6 +637,7 @@
 	CHECK_FAILURE(COSE_Recipient_SetSenderKey(hRecipBad, cn, 0, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
 	CHECK_FAILURE(COSE_Recipient_SetSenderKey(hRecip, NULL, 0, &cose_error), COSE_ERR_INVALID_PARAMETER, CFails++);
 	CHECK_FAILURE(COSE_Recipient_SetSenderKey(hRecip, cn, 3, &cose_error), COSE_ERR_INVALID_PARAMETER, CFails++);
+	CHECK_RETURN(COSE_Recipient_SetSenderKey(hRecip, cn, 0, &cose_error), COSE_ERR_NONE, CFails++);
 
 	CHECK_FAILURE(COSE_Recipient_SetExternal(hRecipNULL, rgb, 10, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
 	CHECK_FAILURE(COSE_Recipient_SetExternal(hRecipBad, rgb, 10, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
@@ -648,4 +650,37 @@
 	CHECK_FAILURE(COSE_Recipient_map_put_int(hRecipBad, 1, cn, COSE_PROTECT_ONLY, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
 	CHECK_FAILURE(COSE_Recipient_map_put_int(hRecip, 1, NULL, COSE_PROTECT_ONLY, &cose_error), COSE_ERR_INVALID_PARAMETER, CFails++);
 	CHECK_FAILURE(COSE_Recipient_map_put_int(hRecip, 1, cn, COSE_PROTECT_ONLY | COSE_UNPROTECT_ONLY, &cose_error), COSE_ERR_INVALID_PARAMETER, CFails++);
-}
\ No newline at end of file
+
+	CHECK_FAILURE(COSE_Recipient_AddRecipient(hRecipNULL, hRecip, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
+	CHECK_FAILURE(COSE_Recipient_AddRecipient(hRecipBad, hRecip, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
+	CHECK_FAILURE(COSE_Recipient_AddRecipient(hRecip, hRecipNULL, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
+	CHECK_FAILURE(COSE_Recipient_AddRecipient(hRecip, hRecipBad, &cose_error), COSE_ERR_INVALID_HANDLE, CFails++);
+
+	COSE_Recipient_Free(hRecip);
+
+	//  Unknown algorithms
+
+	HCOSE_ENVELOPED hEnv = COSE_Enveloped_Init(0, CBOR_CONTEXT_PARAM_COMMA NULL);
+	hRecip = COSE_Recipient_Init(0, CBOR_CONTEXT_PARAM_COMMA NULL);
+
+	CHECK_RETURN(COSE_Enveloped_map_put_int(hEnv, COSE_Header_Algorithm, cn_cbor_int_create(COSE_Algorithm_AES_GCM_128, CBOR_CONTEXT_PARAM_COMMA NULL), COSE_PROTECT_ONLY, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_RETURN(COSE_Enveloped_SetContent(hEnv, (byte *)"This the body", 13, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_RETURN(COSE_Recipient_map_put_int(hRecip, COSE_Header_Algorithm, cn_cbor_int_create(-99, CBOR_CONTEXT_PARAM_COMMA NULL), COSE_UNPROTECT_ONLY, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_RETURN(COSE_Enveloped_AddRecipient(hEnv, hRecip, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_FAILURE(COSE_Enveloped_encrypt(hEnv, &cose_error), COSE_ERR_UNKNOWN_ALGORITHM, CFails++);
+
+	COSE_Enveloped_Free(hEnv);
+	COSE_Recipient_Free(hRecip);
+
+	hEnv = COSE_Enveloped_Init(0, CBOR_CONTEXT_PARAM_COMMA NULL);
+	hRecip = COSE_Recipient_Init(0, CBOR_CONTEXT_PARAM_COMMA NULL);
+
+	CHECK_RETURN(COSE_Enveloped_map_put_int(hEnv, COSE_Header_Algorithm, cn_cbor_int_create(COSE_Algorithm_AES_GCM_128, CBOR_CONTEXT_PARAM_COMMA NULL), COSE_PROTECT_ONLY, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_RETURN(COSE_Enveloped_SetContent(hEnv, (byte *)"This the body", 13, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_RETURN(COSE_Recipient_map_put_int(hRecip, COSE_Header_Algorithm, cn_cbor_string_create("Unknown", CBOR_CONTEXT_PARAM_COMMA NULL), COSE_UNPROTECT_ONLY, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_RETURN(COSE_Enveloped_AddRecipient(hEnv, hRecip, &cose_error), COSE_ERR_NONE, CFails++);
+	CHECK_FAILURE(COSE_Enveloped_encrypt(hEnv, &cose_error), COSE_ERR_UNKNOWN_ALGORITHM, CFails++);
+
+	COSE_Enveloped_Free(hEnv);
+	COSE_Recipient_Free(hRecip);
+}