diff --git a/src/twc-utils.c b/src/twc-utils.c
index ed3b314..3f995ce 100644
--- a/src/twc-utils.c
+++ b/src/twc-utils.c
@@ -32,7 +32,7 @@
  * Convert a hex string to it's binary equivalent of max size bytes.
  */
 void
-twc_hex2bin(const char *hex, size_t size, char *out)
+twc_hex2bin(const char *hex, size_t size, uint8_t *out)
 {
     const char *position = hex;
 
diff --git a/src/twc-utils.h b/src/twc-utils.h
index 5d482b2..56e975f 100644
--- a/src/twc-utils.h
+++ b/src/twc-utils.h
@@ -25,7 +25,7 @@
 #include <tox/tox.h>
 
 void
-twc_hex2bin(const char *hex, size_t size, char *out);
+twc_hex2bin(const char *hex, size_t size, uint8_t *out);
 
 void
 twc_bin2hex(const uint8_t *bin, size_t size, char *out);