diff --git a/stmhal/adc.c b/stmhal/adc.c
index 817b32ea89..7350019eb6 100644
--- a/stmhal/adc.c
+++ b/stmhal/adc.c
@@ -167,7 +167,7 @@ STATIC mp_obj_t adc_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_
         const pin_obj_t *pin = pin_find(pin_obj);
         if ((pin->adc_num & PIN_ADC1) == 0) {
             // No ADC1 function on that pin
-            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "pin %s does not have ADC capabilities", pin->name));
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "pin %s does not have ADC capabilities", qstr_str(pin->name)));
         }
         channel = pin->adc_channel;
     }