diff --git a/py/argcheck.c b/py/argcheck.c
index 465a82c97e..73f3ead269 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -268,6 +268,19 @@ mp_int_t mp_arg_validate_type_int(mp_obj_t obj, qstr arg_name) {
     return an_int;
 }
 
+mp_int_t mp_arg_validate_valid_hex_password(mp_uint_t length, uint8_t *buf) {
+    unsigned int i=0;
+    while (i<length) {
+        if (!(('0' <= buf[i] && buf[i] <= '9') ||
+              ('a' <= buf[i] && buf[i] <= 'f') ||
+              ('A' <= buf[i] && buf[i] <= 'F'))) {
+            mp_raise_ValueError_varg(translate("Invalid hex character in password."));
+        }
+        i++;
+    }
+    return 0;
+}
+
 NORETURN void mp_arg_error_invalid(qstr arg_name) {
     mp_raise_ValueError_varg(translate("Invalid %q"), arg_name);
 }
diff --git a/py/runtime.h b/py/runtime.h
index d154772508..6856bb8c7a 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -114,6 +114,7 @@ mp_obj_t mp_arg_validate_type_in(mp_obj_t obj, const mp_obj_type_t *type, qstr a
 mp_obj_t mp_arg_validate_type_or_none(mp_obj_t obj, const mp_obj_type_t *type, qstr arg_name);
 mp_int_t mp_arg_validate_type_int(mp_obj_t obj, qstr arg_name);
 mp_obj_t mp_arg_validate_type_string(mp_obj_t obj, qstr arg_name);
+mp_int_t mp_arg_validate_valid_hex_password(mp_uint_t length, uint8_t *buf);
 
 static MP_INLINE mp_obj_dict_t *mp_locals_get(void) {
     return MP_STATE_THREAD(dict_locals);
diff --git a/shared-bindings/wifi/Radio.c b/shared-bindings/wifi/Radio.c
index 9475ee3b31..73cceea73b 100644
--- a/shared-bindings/wifi/Radio.c
+++ b/shared-bindings/wifi/Radio.c
@@ -367,7 +367,10 @@ STATIC mp_obj_t wifi_radio_start_ap(size_t n_args, const mp_obj_t *pos_args, mp_
     }
 
     if (authmodes != AUTHMODE_OPEN) {
-        mp_arg_validate_length_range(password.len, 8, 63, MP_QSTR_password);
+        mp_arg_validate_length_range(password.len, 8, 64, MP_QSTR_password);
+        if (password.len==64) {
+            mp_arg_validate_valid_hex_password(password.len, password.buf);
+        }
     }
 
     common_hal_wifi_radio_start_ap(self, ssid.buf, ssid.len, password.buf, password.len, args[ARG_channel].u_int, authmodes, args[ARG_max_connections].u_int);
@@ -445,7 +448,10 @@ STATIC mp_obj_t wifi_radio_connect(size_t n_args, const mp_obj_t *pos_args, mp_m
     if (args[ARG_password].u_obj != mp_const_none) {
         mp_get_buffer_raise(args[ARG_password].u_obj, &password, MP_BUFFER_READ);
         if (password.len != 0) {
-            mp_arg_validate_length_range(password.len, 8, 63, MP_QSTR_password);
+            mp_arg_validate_length_range(password.len, 8, 64, MP_QSTR_password);
+            if (password.len==64) {
+                mp_arg_validate_valid_hex_password(password.len, password.buf);
+            }
         }
     }