diff --git a/common/src/calculate-cpmm-arbitrage.ts b/common/src/calculate-cpmm-arbitrage.ts
index 65e355e441..bf2383dbc9 100644
--- a/common/src/calculate-cpmm-arbitrage.ts
+++ b/common/src/calculate-cpmm-arbitrage.ts
@@ -25,7 +25,11 @@ export function calculateCpmmMultiArbitrageBet(
   collectedFees: Fees
 ) {
   const limitProb =
-    initialLimitProb ?? outcome === 'YES' ? MAX_CPMM_PROB : MIN_CPMM_PROB
+    initialLimitProb !== undefined
+      ? initialLimitProb
+      : outcome === 'YES'
+      ? MAX_CPMM_PROB
+      : MIN_CPMM_PROB
   const result =
     outcome === 'YES'
       ? calculateCpmmMultiArbitrageBetYes(