diff --git a/sql/range_optimizer/partition_pruning.cc b/sql/range_optimizer/partition_pruning.cc
index b9df867..4db6b41 100644
--- a/sql/range_optimizer/partition_pruning.cc
+++ b/sql/range_optimizer/partition_pruning.cc
@@ -731,7 +731,7 @@ static int find_used_partitions(THD *thd, PART_PRUNE_PARAM *ppar,
   ppar->cur_subpart_fields += ppar->is_subpart_keypart[key_tree_part];
   *(ppar->arg_stack_end++) = key_tree;
 
-  if (ignore_part_fields) {
+  if (ignore_part_fields && !ppar->is_subpart_keypart[key_tree_part]) {
     /*
       We come here when a condition on the first partitioning
       fields led to evaluating the partitioning condition