diff --git a/constants/trainer_data_constants.asm b/constants/trainer_data_constants.asm
index 51aef938b..f1556a2b8 100644
--- a/constants/trainer_data_constants.asm
+++ b/constants/trainer_data_constants.asm
@@ -38,3 +38,4 @@ DEF NO_AI EQU 0
 	const TRAINERTYPE_MOVES
 	const TRAINERTYPE_ITEM
 	const TRAINERTYPE_ITEM_MOVES
+DEF NUM_TRAINERTYPES EQU const_value
diff --git a/engine/battle/read_trainer_party.asm b/engine/battle/read_trainer_party.asm
index f4ddfd3e4..b6300e598 100644
--- a/engine/battle/read_trainer_party.asm
+++ b/engine/battle/read_trainer_party.asm
@@ -82,10 +82,12 @@ ReadTrainerParty:
 
 TrainerTypes:
 ; entries correspond to TRAINERTYPE_* constants
+	table_width 2
 	dw TrainerType1 ; level, species
 	dw TrainerType2 ; level, species, moves
 	dw TrainerType3 ; level, species, item
 	dw TrainerType4 ; level, species, item, moves
+	assert_table_length NUM_TRAINERTYPES
 
 TrainerType1:
 ; normal (level, species)