diff --git a/src/nft-contract/approval.ts b/src/nft-contract/approval.ts
index 9bd1745..0a97114 100644
--- a/src/nft-contract/approval.ts
+++ b/src/nft-contract/approval.ts
@@ -166,7 +166,7 @@ export function internalNftRevokeAll({
     assert(predecessorAccountId == token.owner_id, "only token owner can revoke");
 
     //only revoke if the approved account IDs for the token is not empty
-    if (token.approved_account_ids && Object.keys(token.approved_account_ids).length === 0 && Object.getPrototypeOf(token.approved_account_ids) === Object.prototype) {
+    if (token.approved_account_ids && Object.keys(token.approved_account_ids).length !== 0 && Object.getPrototypeOf(token.approved_account_ids) === Object.prototype) {
         //refund the approved account IDs to the caller of the function
         refundApprovedAccountIds(predecessorAccountId, token.approved_account_ids);
         //clear the approved account IDs
@@ -174,4 +174,4 @@ export function internalNftRevokeAll({
         //insert the token back into the tokens_by_id collection with the approved account IDs cleared
         contract.tokensById.set(tokenId, token);
     }
-}
\ No newline at end of file
+}