diff --git a/src/muqsit/arithmexp/expression/optimizer/IdempotenceFoldingExpressionOptimizer.php b/src/muqsit/arithmexp/expression/optimizer/IdempotenceFoldingExpressionOptimizer.php
index 736a084..b67430a 100644
--- a/src/muqsit/arithmexp/expression/optimizer/IdempotenceFoldingExpressionOptimizer.php
+++ b/src/muqsit/arithmexp/expression/optimizer/IdempotenceFoldingExpressionOptimizer.php
@@ -76,6 +76,8 @@ public function run(Parser $parser, Expression $expression) : Expression{
 						$found = true;
 						++$changes;
 					}
+
+					$token->argument_count = count($entry) - 1;
 				}
 			}
 			unset($entry);