diff --git a/Makefile b/Makefile
index 219c2c3..9378403 100644
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,7 @@ SPECVERSION="3.3.1"
 
 APPVERSION_M=1
 APPVERSION_N=2
-APPVERSION_P=0
+APPVERSION_P=1
 APPVERSION=$(APPVERSION_M).$(APPVERSION_N).$(APPVERSION_P)
 
 ifeq ($(TARGET_NAME),TARGET_BLUE)
diff --git a/doc/user/blue-app-openpgp-card.rst b/doc/user/blue-app-openpgp-card.rst
index 6ff16dd..97a778d 100644
--- a/doc/user/blue-app-openpgp-card.rst
+++ b/doc/user/blue-app-openpgp-card.rst
@@ -96,15 +96,7 @@ The application is ready to use!
 From source
 ~~~~~~~~~~~~~
 
-Building from sources requires the the Nano S SDK 1.3.1.4 on firmware 1.3.1. See https://github.com/LedgerHQ/nanos-secure-sdk
-
-The SDK must be slightly modified:
-
-   - replace lib_stusb/STM32_USB_Device_Library/Class/CCID/src/usbd_ccid_if.c
-     and lib_stusb/STM32_USB_Device_Library/Class/CCID/inc/usbd_ccid_if.h by the 
-     one provided in sdk/ directory
-   - edit script.ld and modify the stack size : STACK_SIZE = 832;
-
+Building from sources requires the the Nano S SDK 1.4.2.1 on firmware 1.4.2. See https://github.com/LedgerHQ/nanos-secure-sdk
 
 Refer to the SDK documentation for the compiling/loading...
 
diff --git a/src/gpg_pso.c b/src/gpg_pso.c
index 8d1895c..1d389b0 100644
--- a/src/gpg_pso.c
+++ b/src/gpg_pso.c
@@ -88,7 +88,9 @@ static int gpg_sign(gpg_key_t *sigkey) {
       unsigned char *rs;
 
       key = &sigkey->priv_key.ecfp;
+
       //sign
+      #define RS (G_gpg_vstate.work.io_buffer+(GPG_IO_BUFFER_LENGTH-256))
       if (sigkey->attributes.value[0] == 19) {
         sz = gpg_curve2domainlen(key->curve);
         if ((sz == 0) || (key->d_len != sz)) {
@@ -99,13 +101,13 @@ static int gpg_sign(gpg_key_t *sigkey) {
                            CX_RND_TRNG,
                            CX_NONE,
                            G_gpg_vstate.work.io_buffer, sz,
-                           G_gpg_vstate.work.io_buffer, GPG_IO_BUFFER_LENGTH,
+                           RS, 256,
                            NULL);
         //reencode r,s in MPI format
         gpg_io_discard(0);
       
-        rs_len =  G_gpg_vstate.work.io_buffer[3];
-        rs     =  &G_gpg_vstate.work.io_buffer[4];
+        rs_len =  RS[3];
+        rs     =  &RS[4];
       
         for (i = 0; i<2; i++) {
           if (*rs == 0) {
@@ -124,12 +126,13 @@ static int gpg_sign(gpg_key_t *sigkey) {
                            CX_SHA512, 
                            G_gpg_vstate.work.io_buffer, G_gpg_vstate.io_length,
                            NULL, 0,
-                           G_gpg_vstate.work.io_buffer+128, GPG_IO_BUFFER_LENGTH-128,
+                           RS, 256,
                            NULL);
         gpg_io_discard(0);
-        gpg_io_insert(G_gpg_vstate.work.io_buffer+128, sz);
+        gpg_io_insert(RS, sz);
       }
-      
+      #undef RS
+
       //send
       gpg_pso_reset_PW1();
       return SW_OK;