diff --git a/lib/digsig.c b/lib/digsig.c
index 07be6c1ef4e2..a121cbc5a46b 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -104,16 +104,18 @@ static int digsig_verify_rsa(struct key *key,
 	datap = pkh->mpi;
 	endp = ukp->data + ukp->datalen;
 
-	err = -ENOMEM;
-
 	for (i = 0; i < pkh->nmpi; i++) {
 		unsigned int remaining = endp - datap;
 		pkey[i] = mpi_read_from_buffer(datap, &remaining);
-		if (!pkey[i])
+		if (IS_ERR(pkey[i])) {
+			err = PTR_ERR(pkey[i]);
 			goto err;
+		}
 		datap += remaining;
 	}
 
+	err = -ENOMEM;
+
 	mblen = mpi_get_nbits(pkey[0]);
 	mlen = DIV_ROUND_UP(mblen, 8);
 
@@ -126,8 +128,10 @@ static int digsig_verify_rsa(struct key *key,
 
 	nret = siglen;
 	in = mpi_read_from_buffer(sig, &nret);
-	if (!in)
+	if (IS_ERR(in)) {
+		err = PTR_ERR(in);
 		goto err;
+	}
 
 	res = mpi_alloc(mpi_get_nlimbs(in) * 2);
 	if (!res)
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index eda34aba017e..350abaf4bee7 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -86,12 +86,12 @@ MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
 	MPI val = NULL;
 
 	if (*ret_nread < 2)
-		goto leave;
+		return ERR_PTR(-EINVAL);
 	nbits = buffer[0] << 8 | buffer[1];
 
 	if (nbits > MAX_EXTERN_MPI_BITS) {
 		pr_info("MPI: mpi too large (%u bits)\n", nbits);
-		goto leave;
+		return ERR_PTR(-EINVAL);
 	}
 	buffer += 2;
 	nread = 2;
@@ -100,7 +100,7 @@ MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
 	nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
 	val = mpi_alloc(nlimbs);
 	if (!val)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 	i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
 	i %= BYTES_PER_MPI_LIMB;
 	val->nbits = nbits;