diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 2ed1e44c18..2f84f30423 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -1023,8 +1023,12 @@ gen_partprune_steps_internal(GeneratePruningStepsContext *context,
 		 * If the clause contradicts the partition constraint, mark the clause
 		 * as contradictory and we're done.  This is particularly helpful to
 		 * prune the default partition.
+		 *
+		 * However, we skip this if constraint_exclusion is set to ON, because
+		 * this check will be done by set_rel_size later on anyway.
 		 */
-		if (context->rel->partition_qual)
+		if (context->rel->partition_qual &&
+			constraint_exclusion != CONSTRAINT_EXCLUSION_ON)
 		{
 			List	   *partconstr;