diff --git a/sys/ztimer/convert_frac.c b/sys/ztimer/convert_frac.c
index 6980fd83d2..4cfbbf98e3 100644
--- a/sys/ztimer/convert_frac.c
+++ b/sys/ztimer/convert_frac.c
@@ -100,7 +100,7 @@ void ztimer_convert_frac_init(ztimer_convert_frac_t *self,
 
     ztimer_convert_frac_compute_scale(self, freq_self, freq_lower);
     if (freq_self < freq_lower) {
-        self->super.super.max_value = frac_scale(&self->scale_set, UINT32_MAX);
+        self->super.super.max_value = frac_scale(&self->scale_now, UINT32_MAX);
         ztimer_init_extend(&self->super.super);
     }
     else {