diff --git a/src/tox-weechat-commands.c b/src/tox-weechat-commands.c
index 70d1218..09db0fe 100644
--- a/src/tox-weechat-commands.c
+++ b/src/tox-weechat-commands.c
@@ -125,7 +125,7 @@ tox_weechat_cmd_friend(void *data, struct t_gui_buffer *buffer,
     else if (argc >= 3 && (weechat_strcasecmp(argv[1], "add") == 0))
     {
         char address[TOX_FRIEND_ADDRESS_SIZE];
-        tox_weechat_hex2bin(argv[2], address);
+        tox_weechat_hex2bin(argv[2], TOX_FRIEND_ADDRESS_SIZE * 2, address);
 
         char *message;
         if (argc == 3 || strlen(argv_eol[3]) == 0)
diff --git a/src/tox-weechat-friend-requests.c b/src/tox-weechat-friend-requests.c
index e84bef7..bd4e34d 100644
--- a/src/tox-weechat-friend-requests.c
+++ b/src/tox-weechat-friend-requests.c
@@ -141,7 +141,7 @@ tox_weechat_friend_request_init_identity(struct t_tox_weechat_identity *identity
         json_t *json_message = json_object_get(json_request,
                                                tox_weechat_json_friend_request_key_message);
 
-        tox_weechat_hex2bin(json_string_value(json_id), client_id);
+        tox_weechat_hex2bin(json_string_value(json_id), TOX_CLIENT_ID_SIZE * 2, client_id);
         message = json_string_value(json_message);
 
         tox_weechat_friend_request_add(identity,
diff --git a/src/tox-weechat-identities.c b/src/tox-weechat-identities.c
index 6a6679d..b28ad3a 100644
--- a/src/tox-weechat-identities.c
+++ b/src/tox-weechat-identities.c
@@ -165,7 +165,7 @@ int
 tox_weechat_bootstrap_tox(Tox *tox, const char *address, uint16_t port, const char *public_key)
 {
     char binary_key[TOX_FRIEND_ADDRESS_SIZE];
-    tox_weechat_hex2bin(public_key, binary_key);
+    tox_weechat_hex2bin(public_key, TOX_FRIEND_ADDRESS_SIZE * 2, binary_key);
 
     int result = tox_bootstrap_from_address(tox,
                                             address,
diff --git a/src/tox-weechat-utils.c b/src/tox-weechat-utils.c
index ad80b8a..76a70be 100644
--- a/src/tox-weechat-utils.c
+++ b/src/tox-weechat-utils.c
@@ -30,12 +30,11 @@
 #include "tox-weechat-utils.h"
 
 void
-tox_weechat_hex2bin(const char *hex, char *out)
+tox_weechat_hex2bin(const char *hex, size_t length, char *out)
 {
-    size_t length = strlen(hex) / 2;
     const char *position = hex;
 
-    for (size_t i = 0; i < length; ++i)
+    for (size_t i = 0; i < length / 2; ++i)
     {
         sscanf(position, "%2hhx", &out[i]);
         position += 2;
diff --git a/src/tox-weechat-utils.h b/src/tox-weechat-utils.h
index d8c4fdf..3f8a1fd 100644
--- a/src/tox-weechat-utils.h
+++ b/src/tox-weechat-utils.h
@@ -26,7 +26,7 @@
 #include <tox/tox.h>
 
 void
-tox_weechat_hex2bin(const char *hex, char *out);
+tox_weechat_hex2bin(const char *hex, size_t length, char *out);
 
 void
 tox_weechat_bin2hex(const uint8_t *bin, size_t size, char *out);