diff --git a/Makefile b/Makefile
index a9e0191..493e6e6 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,8 @@ obj = $(src:.c=.o) uECC.o
 
 LIBCBOR = tinycbor/lib/libtinycbor.a
 LDFLAGS = -Wl,--gc-sections $(LIBCBOR)
-CFLAGS = -O2 -fdata-sections -ffunction-sections 
+CFLAGS = -O2 -fdata-sections -ffunction-sections
+CFLAGS += -Wall -Werror
 
 INCLUDES = -I./tinycbor/src -I./crypto/sha256 -I./crypto/micro-ecc/ -Icrypto/tiny-AES-c/ -I./fido2/ -I./pc -I./fido2/extensions
 
diff --git a/crypto/aes-gcm/aes_gcm.c b/crypto/aes-gcm/aes_gcm.c
index 74786dc..6cfcc5e 100644
--- a/crypto/aes-gcm/aes_gcm.c
+++ b/crypto/aes-gcm/aes_gcm.c
@@ -29,7 +29,7 @@ int main(int argc, char * argv[])
     uint8_t key[32];
     uint8_t authtag[BLOCK_SIZE];
 
-    uint8_t * authtag1 = "\x53\x0f\x8a\xfb\xc7\x45\x36\xb9\xa9\x63\xb4\xf1\xc4\xcb\x73\x8b";
+    // uint8_t * authtag1 = (uint8_t *)"\x53\x0f\x8a\xfb\xc7\x45\x36\xb9\xa9\x63\xb4\xf1\xc4\xcb\x73\x8b";
 
     memset(nonce,0,16);
     memset(key,0,16);
diff --git a/fido2/ctap.c b/fido2/ctap.c
index 2e62a01..90e2282 100644
--- a/fido2/ctap.c
+++ b/fido2/ctap.c
@@ -1290,7 +1290,7 @@ void ctap_init()
     {
         printf1(TAG_STOR,"pin code: \"%s\"\n", STATE.pin_code);
         crypto_sha256_init();
-        crypto_sha256_update(STATE.pin_code, strnlen(STATE.pin_code, NEW_PIN_ENC_MAX_SIZE));
+        crypto_sha256_update(STATE.pin_code, strnlen((char *)STATE.pin_code, NEW_PIN_ENC_MAX_SIZE));
         crypto_sha256_final(PIN_CODE_HASH);
         printf1(TAG_STOR, "attempts_left: %d\n", STATE.remaining_tries);
     }
diff --git a/pc/app.h b/pc/app.h
index 692e291..a45833f 100644
--- a/pc/app.h
+++ b/pc/app.h
@@ -14,6 +14,8 @@
 
 #define DEBUG_LEVEL 1
 
+#define ENABLE_U2F
+
 //#define BRIDGE_TO_WALLET
 
 void printing_init();
diff --git a/pc/device.c b/pc/device.c
index 43ad521..b76082f 100644
--- a/pc/device.c
+++ b/pc/device.c
@@ -8,6 +8,7 @@
 #include <time.h>
 #include <string.h>
 #include <unistd.h>
+#include <signal.h>
 
 #include "device.h"
 #include "cbor.h"
@@ -136,13 +137,20 @@ void usbhid_close()
     udp_close(serverfd);
 }
 
+void int_handler(int i)
+{
+    usbhid_close();
+    printf("SIGINT... exiting.\n");
+    exit(0);
+}
 
 void device_init()
 {
+    signal(SIGINT, int_handler);
+
     usbhid_init();
 
     authenticator_initialize();
-
 }
 
 
@@ -181,7 +189,6 @@ int ctap_user_verification(uint8_t arg)
 uint32_t ctap_atomic_count(int sel)
 {
     static uint32_t counter1 = 25;
-    static uint32_t counter2 = 25;
     /*return 713;*/
     if (sel == 0)
     {
@@ -197,15 +204,21 @@ uint32_t ctap_atomic_count(int sel)
 
 int ctap_generate_rng(uint8_t * dst, size_t num)
 {
+    int ret;
     FILE * urand = fopen("/dev/urandom","r");
     if (urand == NULL)
     {
         perror("fopen");
         exit(1);
     }
-    fread(dst, 1, num, urand);
+    ret = fread(dst, 1, num, urand);
     fclose(urand);
 
+    if (ret != num)
+    {
+        perror("fwrite");
+        exit(1);
+    }
     /*memset(dst,0xaa,num);*/
 
     return 1;
@@ -305,7 +318,6 @@ int authenticator_is_backup_initialized()
     AuthenticatorState * state = (AuthenticatorState*) header;
     FILE * f;
     int ret;
-    uint8_t * mem;
 
     printf("state file exists\n");
     f = fopen(backup_file, "rb");