diff --git a/BrainATUMtome/serialpackage.cpp b/BrainATUMtome/serialpackage.cpp
index 07ce36a..f15be0b 100644
--- a/BrainATUMtome/serialpackage.cpp
+++ b/BrainATUMtome/serialpackage.cpp
@@ -24,10 +24,10 @@ QString SerialPackage::parse(bool &ok, const QString &message)
     quint8 checksumReceived = 0;
     if (!unpack(checksumReceived, buffer.mid(buffer.size() - 2, 2)))
         ok = false;
-    ok = (checksumReceived == checksum(message));
 
     // remove checksum from buffer
     buffer.remove(buffer.size() - 2, 2);
+    ok = (checksumReceived == checksum(buffer));
 
     return buffer;
 }