diff --git a/ui/open.c b/ui/open.c
index 1cc4929..fce77a0 100644
--- a/ui/open.c
+++ b/ui/open.c
@@ -1,15 +1,15 @@
 #include "../params.h"
-#include "../xmss_core.h"
+#include "../xmss.h"
 #include <stdio.h>
 
 #define MLEN 32
 
 #ifdef XMSSMT
     #define XMSS_PARSE_OID xmssmt_parse_oid
-    #define XMSS_CORE_SIGN_OPEN xmssmt_core_sign_open
+    #define XMSS_SIGN_OPEN xmssmt_sign_open
 #else
     #define XMSS_PARSE_OID xmss_parse_oid
-    #define XMSS_CORE_SIGN_OPEN xmss_core_sign_open
+    #define XMSS_SIGN_OPEN xmss_sign_open
 #endif
 
 int main(int argc, char **argv) {
@@ -34,15 +34,16 @@ int main(int argc, char **argv) {
     fread(&oid, 1, XMSS_OID_LEN, keypair);
     XMSS_PARSE_OID(&params, oid);
 
-    unsigned char pk[params.pk_bytes];
+    unsigned char pk[XMSS_OID_LEN + params.pk_bytes];
     unsigned char sm[params.sig_bytes + MLEN];
     unsigned char m[params.sig_bytes + MLEN];
     unsigned long long mlen;
 
-    fread(pk, 1, params.pk_bytes, keypair);
+    fseek(keypair, 0, SEEK_SET);
+    fread(pk, 1, XMSS_OID_LEN + params.pk_bytes, keypair);
     fread(sm, 1, params.sig_bytes + MLEN, stdin);
 
-    ret = XMSS_CORE_SIGN_OPEN(&params, m, &mlen, sm, params.sig_bytes + MLEN, pk);
+    ret = XMSS_SIGN_OPEN(m, &mlen, sm, params.sig_bytes + MLEN, pk);
 
     if (ret) {
         printf("Verification failed!\n");
diff --git a/ui/sign.c b/ui/sign.c
index 574fa58..48f7aca 100644
--- a/ui/sign.c
+++ b/ui/sign.c
@@ -1,15 +1,15 @@
 #include "../params.h"
-#include "../xmss_core.h"
+#include "../xmss.h"
 #include <stdio.h>
 
 #define MLEN 32
 
 #ifdef XMSSMT
     #define XMSS_PARSE_OID xmssmt_parse_oid
-    #define XMSS_CORE_SIGN xmssmt_core_sign
+    #define XMSS_SIGN xmssmt_sign
 #else
     #define XMSS_PARSE_OID xmss_parse_oid
-    #define XMSS_CORE_SIGN xmss_core_sign
+    #define XMSS_SIGN xmss_sign
 #endif
 
 int main(int argc, char **argv) {
@@ -42,17 +42,20 @@ int main(int argc, char **argv) {
     fread(&oid_sk, 1, XMSS_OID_LEN, keypair);
     XMSS_PARSE_OID(&params, oid_sk);
 
-    unsigned char sk[params.sk_bytes];
+    unsigned char sk[XMSS_OID_LEN + params.sk_bytes];
     unsigned char m[MLEN];
     unsigned char sm[params.sig_bytes + MLEN];
     unsigned long long smlen;
 
-    fread(sk, 1, params.sk_bytes, keypair);
+    /* fseek back to start of sk. */
+    fseek(keypair, -((long int)XMSS_OID_LEN), SEEK_CUR);
+    fread(sk, 1, XMSS_OID_LEN + params.sk_bytes, keypair);
     fread(m, 1, MLEN, stdin);
-    XMSS_CORE_SIGN(&params, sk, sm, &smlen, m, MLEN);
+
+    XMSS_SIGN(sk, sm, &smlen, m, MLEN);
 
     fseek(keypair, -((long int)params.sk_bytes), SEEK_CUR);
-    fwrite(sk, 1, params.sk_bytes, keypair);
+    fwrite(sk + XMSS_OID_LEN, 1, params.sk_bytes, keypair);
     fwrite(sm, 1, params.sig_bytes + MLEN, stdout);
 
     fclose(keypair);