diff --git a/cmdbuf.c b/cmdbuf.c
index b11bd00..b268f1f 100644
--- a/cmdbuf.c
+++ b/cmdbuf.c
@@ -31,7 +31,7 @@ bool cmd_match_hex_number(CommandBuf *cmd, uint32_t *value) {
     return true;
 }
 
-bool cmd_match_hex_bytes(CommandBuf *cmd, const uint32_t count, char *value) {
+bool cmd_match_hex_bytes(CommandBuf *cmd, const uint32_t count, uint8_t *value) {
     if (cmd->len < (count * 2)) return false;
     for (size_t i = 0; i < count; ++i) {
         char hi, lo;
diff --git a/include/cmdbuf.h b/include/cmdbuf.h
index 082a4e3..9bf5920 100644
--- a/include/cmdbuf.h
+++ b/include/cmdbuf.h
@@ -15,6 +15,6 @@ bool cmd_match_str(CommandBuf *cmd, const char *str);
 /* Try to consume a base-16 number, and return the value. */
 bool cmd_match_hex_number(CommandBuf *cmd, uint32_t *value);
 /* Try to consume a hex-encoded list of bytes, and return the value. */
-bool cmd_match_hex_bytes(CommandBuf *cmd, const uint32_t count, char *value);
+bool cmd_match_hex_bytes(CommandBuf *cmd, const uint32_t count, uint8_t *value);
 
 #endif
\ No newline at end of file
diff --git a/server.c b/server.c
index f51284c..06c71cd 100644
--- a/server.c
+++ b/server.c
@@ -160,7 +160,7 @@ int handle_command(RdbResponse *res, CommandBuf *cmd, VB *sim, bool *running) {
     if (cmd_match_str(cmd, "P")) {
         // write a register.
         uint32_t reg_no;
-        char reg_bytes[4];
+        uint8_t reg_bytes[4];
         if (!cmd_match_hex_number(cmd, &reg_no)) return -1;
         if (!cmd_match_str(cmd, "=")) return -1;
         if (!cmd_match_hex_bytes(cmd, 4, reg_bytes)) return -1;