diff --git a/addons/material_maker/engine/gen_iterate_buffer.gd b/addons/material_maker/engine/gen_iterate_buffer.gd
index 1dec3aea..a3f1186f 100644
--- a/addons/material_maker/engine/gen_iterate_buffer.gd
+++ b/addons/material_maker/engine/gen_iterate_buffer.gd
@@ -42,6 +42,7 @@ func get_output_defs() -> Array:
 	return [ { type="rgba" }, { type="rgba" } ]
 
 func source_changed(input_port_index : int) -> void:
+	current_iteration = 0
 	call_deferred("update_shader", input_port_index)
 
 func follow_input(input_index : int) -> Array: