diff --git a/p4src/actions_delta_checksum.p4 b/p4src/actions_delta_checksum.p4
index 0107e24..751f7f8 100644
--- a/p4src/actions_delta_checksum.p4
+++ b/p4src/actions_delta_checksum.p4
@@ -61,7 +61,7 @@ action delta_udp_from_v4_to_v6()
         tmp = tmp + 1;
         tmp[16:16] = 0;
     }
-    tmp = tmp + (bit<17>) (0xffff - meta.v6sum);
+    tmp = tmp + (bit<17>) (0xffff - meta.v4sum);
     if (tmp[16:16] == 1) {
         tmp = tmp + 1;
         tmp[16:16] = 0;
@@ -79,7 +79,7 @@ action delta_tcp_from_v4_to_v6()
         tmp = tmp + 1;
         tmp[16:16] = 0;
     }
-    tmp = tmp + (bit<17>) (0xffff - meta.v6sum);
+    tmp = tmp + (bit<17>) (0xffff - meta.v4sum);
     if (tmp[16:16] == 1) {
         tmp = tmp + 1;
         tmp[16:16] = 0;