1 files changed, 2 insertions, 1 deletions
diff --git a/sql/opt_sum.cc b/sql/opt_sum.cc
index ddeeb44c82b..33c8eadc065 100644
--- a/sql/opt_sum.cc
+++ b/sql/opt_sum.cc
@@ -677,7 +677,8 @@ static bool find_key_for_maxmin(bool max_fl, TABLE_REF *ref,
               If key_part2 may be NULL, then we want to find the first row
               that is not null
             */
-            ref->key_buff[ref->key_length++]= 1;
+            ref->key_buff[ref->key_length]= 1;
+            ref->key_length+= part->store_length;
             *range_fl&= ~NO_MIN_RANGE;
             *range_fl|= NEAR_MIN;                // > NULL
           }