diff --git a/Makefile b/Makefile
index bef30d6c..e5fc639a 100644
--- a/Makefile
+++ b/Makefile
@@ -24,7 +24,7 @@ APP_PATH = ""
 APP_LOAD_PARAMS= --curve secp256k1 $(COMMON_LOAD_PARAMS)
 
 APPVERSION_M=2
-APPVERSION_N=1
+APPVERSION_N=2
 APPVERSION_P=0
 APPVERSION=$(APPVERSION_M).$(APPVERSION_N).$(APPVERSION_P)
 APP_LOAD_FLAGS=--appFlags 0xa50
diff --git a/include/swap_lib_calls.h b/include/swap_lib_calls.h
index 378b93c8..0f59a452 100644
--- a/include/swap_lib_calls.h
+++ b/include/swap_lib_calls.h
@@ -1,7 +1,14 @@
-#ifndef SWAP_LIB_CALLS
-#define SWAP_LIB_CALLS
+#pragma once
+
+/* This file is the shared API between Exchange and the apps started in Library mode for Exchange
+ *
+ * DO NOT MODIFY THIS FILE IN APPLICATIONS OTHER THAN EXCHANGE
+ * On modification in Exchange, forward the changes to all applications supporting Exchange
+ */
 
 #include "stdbool.h"
+#include "stdint.h"
+#include "btchip_context.h"
 
 #define RUN_APPLICATION 1
 
@@ -11,15 +18,25 @@
 
 #define GET_PRINTABLE_AMOUNT 4
 
+/*
+ * Amounts are stored as bytes, with a max size of 16 (see protobuf
+ * specifications). Max 16B integer is 340282366920938463463374607431768211455
+ * in decimal, which is a 32-long char string.
+ * The printable amount also contains spaces, the ticker symbol (with variable
+ * size, up to 12 in Ethereum for instance) and a terminating null byte, so 50
+ * bytes total should be a fair maximum.
+ */
+#define MAX_PRINTABLE_AMOUNT_SIZE 50
+
 // structure that should be send to specific coin application to get address
 typedef struct check_address_parameters_s {
     // IN
-    unsigned char* coin_configuration;
-    unsigned char coin_configuration_length;
+    uint8_t *coin_configuration;
+    uint8_t coin_configuration_length;
     // serialized path, segwit, version prefix, hash used, dictionary etc.
-    // fields and serialization format depends on spesific coin app
-    unsigned char* address_parameters;
-    unsigned char address_parameters_length;
+    // fields and serialization format depends on specific coin app
+    uint8_t *address_parameters;
+    uint8_t address_parameters_length;
     char *address_to_check;
     char *extra_id_to_check;
     // OUT
@@ -29,25 +46,36 @@ typedef struct check_address_parameters_s {
 // structure that should be send to specific coin application to get printable amount
 typedef struct get_printable_amount_parameters_s {
     // IN
-    unsigned char* coin_configuration;
-    unsigned char coin_configuration_length;
-    unsigned char* amount;
-    unsigned char amount_length;
+    uint8_t *coin_configuration;
+    uint8_t coin_configuration_length;
+    uint8_t *amount;
+    uint8_t amount_length;
     bool is_fee;
     // OUT
-    char printable_amount[30];
-    // int result;
+    char printable_amount[MAX_PRINTABLE_AMOUNT_SIZE];
 } get_printable_amount_parameters_t;
 
 typedef struct create_transaction_parameters_s {
-    unsigned char* coin_configuration;
-    unsigned char coin_configuration_length;
-    unsigned char* amount;
-    unsigned char amount_length;
-    unsigned char* fee_amount;
-    unsigned char fee_amount_length;
+    // IN
+    uint8_t *coin_configuration;
+    uint8_t coin_configuration_length;
+    uint8_t *amount;
+    uint8_t amount_length;
+    uint8_t *fee_amount;
+    uint8_t fee_amount_length;
     char *destination_address;
     char *destination_address_extra_id;
+    // OUT
+    uint8_t result;
 } create_transaction_parameters_t;
 
-#endif
+typedef struct libargs_s {
+    unsigned int id;
+    unsigned int command;
+    btchip_altcoin_config_t *coin_config;
+    union {
+        check_address_parameters_t *check_address;
+        create_transaction_parameters_t *create_transaction;
+        get_printable_amount_parameters_t *get_printable_amount;
+    };
+} libargs_t;
diff --git a/src/btchip.c b/src/btchip.c
index 9b40a012..7e7ef173 100644
--- a/src/btchip.c
+++ b/src/btchip.c
@@ -24,6 +24,8 @@
 #include "btchip_apdu_constants.h"
 #include "btchip_display_variables.h"
 
+#include "handle_swap_sign_transaction.h"
+
 #define BTCHIP_TECHNICAL_NOT_IMPLEMENTED 0x99
 
 #define COMMON_CLA               0xB0
@@ -167,7 +169,7 @@ void app_main(void) {
                         btchip_context_D.outLength);
 
         if (btchip_context_D.called_from_swap && vars.swap_data.should_exit) {
-            os_sched_exit(0);
+            finalize_exchange_sign_transaction(btchip_context_D.sw == BTCHIP_SW_OK);
         }
 
         PRINTF("New APDU received:\n%.*H\n", btchip_context_D.inLength, G_io_apdu_buffer);
diff --git a/src/handle_swap_sign_transaction.c b/src/handle_swap_sign_transaction.c
index 40479c4f..1c2dc971 100644
--- a/src/handle_swap_sign_transaction.c
+++ b/src/handle_swap_sign_transaction.c
@@ -6,6 +6,12 @@
 #include "usbd_core.h"
 #include "ux.h"
 
+#ifdef HAVE_NBGL
+#include "nbgl_use_case.h"
+#endif
+
+// Save the BSS address where we will write the return value when finished
+static uint8_t *G_swap_sign_return_value_address;
 
 bool copy_transaction_parameters(create_transaction_parameters_t* sign_transaction_params) {
     // first copy parameters to stack, and then to global data.
@@ -22,6 +28,14 @@ bool copy_transaction_parameters(create_transaction_parameters_t* sign_transacti
     // input {0xEE, 0x00, 0xFF} should be stored like {0x00, 0x00, 0x00, 0x00, 0x00, 0xEE, 0x00, 0xFF}
     memcpy(stack_data.amount + 8 - sign_transaction_params->amount_length, sign_transaction_params->amount, sign_transaction_params->amount_length);
     memcpy(stack_data.fees + 8 - sign_transaction_params->fee_amount_length, sign_transaction_params->fee_amount, sign_transaction_params->fee_amount_length);
+
+    // Erase values inherited from Exchange app
+    os_explicit_zero_BSS_segment();
+
+    // Keep the address at which we'll reply the signing status
+    G_swap_sign_return_value_address = &sign_transaction_params->result;
+
+    // Copy from stack back to global data segment
     memcpy(&vars.swap_data, &stack_data, sizeof(stack_data));
     return true;
 }
@@ -32,6 +46,9 @@ void handle_swap_sign_transaction(btchip_altcoin_config_t *config) {
     btchip_context_D.called_from_swap = 1;
     io_seproxyhal_init();
     UX_INIT();
+#ifdef HAVE_NBGL
+    nbgl_useCaseSpinner("Signing");
+#endif  // HAVE_BAGL
     USB_power(0);
     USB_power(1);
     //ui_idle();
@@ -45,4 +62,9 @@ void handle_swap_sign_transaction(btchip_altcoin_config_t *config) {
     BLE_power(1, "Nano X");
 #endif // HAVE_BLE
     app_main();
-}
\ No newline at end of file
+}
+
+void __attribute__((noreturn)) finalize_exchange_sign_transaction(bool is_success) {
+    *G_swap_sign_return_value_address = is_success;
+    os_lib_end();
+}
diff --git a/src/handle_swap_sign_transaction.h b/src/handle_swap_sign_transaction.h
index 46262601..85f5bd86 100644
--- a/src/handle_swap_sign_transaction.h
+++ b/src/handle_swap_sign_transaction.h
@@ -8,4 +8,6 @@ bool copy_transaction_parameters(create_transaction_parameters_t* sign_transacti
 
 void handle_swap_sign_transaction(btchip_altcoin_config_t *config);
 
-#endif // _HANDLE_SWAP_SIGN_TRANSACTION_H_
\ No newline at end of file
+void __attribute__((noreturn)) finalize_exchange_sign_transaction(bool is_success);
+
+#endif // _HANDLE_SWAP_SIGN_TRANSACTION_H_
diff --git a/src/main.c b/src/main.c
index 2436858e..449eea21 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1225,19 +1225,7 @@ void coin_main(btchip_altcoin_config_t *coin_config) {
     app_exit();
 }
 
-struct libargs_s {
-    unsigned int id;
-    unsigned int command;
-    btchip_altcoin_config_t *coin_config;
-    union {
-        check_address_parameters_t *check_address;
-        create_transaction_parameters_t *create_transaction;
-        get_printable_amount_parameters_t *get_printable_amount;
-    };
-};
-
-static void library_main_helper(struct libargs_s *args) {
-    check_api_level(CX_COMPAT_APILEVEL);
+static void library_main_helper(libargs_t *args) {
     PRINTF("Inside a library \n");
     switch (args->command) {
         case CHECK_ADDRESS:
@@ -1253,10 +1241,6 @@ static void library_main_helper(struct libargs_s *args) {
             }
             break;
         case GET_PRINTABLE_AMOUNT:
-            // ensure result is zero if an exception is thrown (compatibility breaking, disabled
-            // until LL is ready)
-            // args->get_printable_amount->result = 0;
-            // args->get_printable_amount->result =
             handle_get_printable_amount(args->get_printable_amount, args->coin_config);
             break;
         default:
@@ -1264,7 +1248,7 @@ static void library_main_helper(struct libargs_s *args) {
     }
 }
 
-void library_main(struct libargs_s *args) {
+void library_main(libargs_t *args) {
     btchip_altcoin_config_t coin_config;
     if (args->coin_config == NULL) {
         init_coin_config(&coin_config);
@@ -1333,7 +1317,7 @@ __attribute__((section(".boot"))) int main(int arg0) {
         coin_main(NULL);
         return 0;
     }
-    struct libargs_s *args = (struct libargs_s *) arg0;
+    libargs_t *args = (libargs_t *) arg0;
     if (args->id != 0x100) {
         app_exit();
         return 0;