diff --git a/src/js/slaveCostJS.js b/src/js/slaveCostJS.js
index b04d21807b9099b7eee7595c117d579c63f95406..bb012d8699d1612e320f7d5e351b57561d85ac3a 100644
--- a/src/js/slaveCostJS.js
+++ b/src/js/slaveCostJS.js
@@ -2288,7 +2288,7 @@ globalThis.slaveCost = function(slave, isStartingSlave = false, followLaws = fal
 
 	function costTooltip() {
 		// Make a link. Clicking the link will display detailed info about that over the top of the page (tooltip-style)
-		const span = App.UI.DOM.makeElement("span", cashFormat(cost));
+		const span = App.UI.DOM.makeElement("span", cashFormat(cost).toString());
 		if (V.cheatMode || V.debugMode) {
 			span.tabIndex = 0;
 			span.classList.add("has-tooltip");