diff --git a/evolver.amlg b/evolver.amlg
index c1e2fa7..e5985cb 100644
--- a/evolver.amlg
+++ b/evolver.amlg
@@ -126,7 +126,7 @@
 		(assign_to_entities "_population_manifest" (assoc metadata
 			(map
 				(lambda
-					(set (current_value) "age"
+					(modify (current_value) "age"
 						(+ 1 (get (current_value) "age"))))
 				(retrieve_from_entity "_population_manifest" "metadata")
 			)
@@ -152,7 +152,7 @@
 					;update score
 					(assign (assoc
 							metadata
-								(set metadata (list id "score")
+								(modify metadata (list id "score")
 
 									;if don't have an existing score, use the current one
 									(if (= prev_score .null)
@@ -170,7 +170,7 @@
 
 				;initialize record for this entity
 				(assign (assoc
-					metadata (set metadata
+					metadata (modify metadata
 						id
 							(assoc
 								score score
diff --git a/tic_tac_toe.amlg b/tic_tac_toe.amlg
index 88735ab..7f3efd4 100644
--- a/tic_tac_toe.amlg
+++ b/tic_tac_toe.amlg
@@ -24,9 +24,9 @@
 					(<= 0 column 2)
 					(= (get board [row column]) 0)
 			)
-			(set board
+			(modify board
 				row
-				(set (get board row) column player)
+				(modify (get board row) column player)
 			)
 			
 			;else return the board as it is