diff --git a/xchange-ftx/src/main/java/org/knowm/xchange/ftx/service/FtxDigest.java b/xchange-ftx/src/main/java/org/knowm/xchange/ftx/service/FtxDigest.java
index 563920a0eaf..865cc73db99 100644
--- a/xchange-ftx/src/main/java/org/knowm/xchange/ftx/service/FtxDigest.java
+++ b/xchange-ftx/src/main/java/org/knowm/xchange/ftx/service/FtxDigest.java
@@ -30,7 +30,7 @@ public String digestParams(RestInvocation restInvocation) {
             + restInvocation.getHttpMethod().toUpperCase()
             + restInvocation.getPath();
 
-    if(restInvocation.getQueryString() != null){
+    if(!restInvocation.getQueryString().isEmpty()){
       message += "?"+restInvocation.getQueryString();
     }