diff --git a/openair2/LAYER2/MAC/pre_processor.c b/openair2/LAYER2/MAC/pre_processor.c
index e720c1dfec..bf8202f622 100644
--- a/openair2/LAYER2/MAC/pre_processor.c
+++ b/openair2/LAYER2/MAC/pre_processor.c
@@ -734,7 +734,7 @@ void calculate_max_mcs_min_rb(module_id_t mod_id,
 
   /* find maximum MCS */
   while ((phr - *tx_power < 0 || tbs > bytes) && *mcs > 3) {
-    mcs--;
+    (*mcs)--;
     tbs = get_TBS_UL(*mcs, rb_table[*rb_index]);
     *tx_power = estimate_ue_tx_power(tbs * 8, rb_table[*rb_index], 0, Ncp, 0);
   }