diff --git a/functions/src/place-bet.ts b/functions/src/place-bet.ts
index 8fb5179d..3591598f 100644
--- a/functions/src/place-bet.ts
+++ b/functions/src/place-bet.ts
@@ -30,15 +30,7 @@ const bodySchema = z.object({
 
 const binarySchema = z.object({
   outcome: z.enum(['YES', 'NO']),
-  limitProb: z
-    .number()
-    .gte(0.001)
-    .lte(0.999)
-    .refine(
-      (p) => Math.round(p * 100) === p * 100,
-      'limitProb must be in increments of 0.01 (i.e. whole percentage points)'
-    )
-    .optional(),
+  limitProb: z.number().gte(0.001).lte(0.999).optional(),
 })
 
 const freeResponseSchema = z.object({
@@ -92,6 +84,15 @@ export const placebet = newEndpoint({}, async (req, auth) => {
       ) {
         const { outcome, limitProb } = validate(binarySchema, req.body)
 
+        if (limitProb !== undefined && outcomeType === 'BINARY') {
+          const isRounded = Math.round(limitProb * 100) === limitProb * 100
+          if (!isRounded)
+            throw new APIError(
+              400,
+              'limitProb must be in increments of 0.01 (i.e. whole percentage points)'
+            )
+        }
+
         const unfilledBetsSnap = await trans.get(
           getUnfilledBetsQuery(contractDoc)
         )