diff --git a/p4src/actions_delta_checksum.p4 b/p4src/actions_delta_checksum.p4
index 56dbf55..0cf219f 100644
--- a/p4src/actions_delta_checksum.p4
+++ b/p4src/actions_delta_checksum.p4
@@ -12,7 +12,6 @@ action v4sum() {
     tmp = tmp + (bit<16>) hdr.ipv4.totalLen -20;                // 16 bit
     tmp = tmp + (bit<16>) hdr.ipv4.protocol;                    // 8 bit
 
-    tmp = ~tmp;
     meta.v4sum = tmp;
 }
 
@@ -40,7 +39,6 @@ action v6sum() {
     tmp = tmp + (bit<16>) hdr.ipv6.payload_length;              // 16 bit
     tmp = tmp + (bit<16>) hdr.ipv6.next_header;                 // 8 bit
 
-    tmp = ~tmp;
     meta.v6sum = tmp;
 }
 
@@ -53,29 +51,21 @@ action delta_prepare()
 action delta_udp_from_v4_to_v6()
 {
     delta_prepare();
-    hdr.udp.checksum = hdr.udp.checksum + meta.v6sum;
 
-    /* prevent negative wrap around that loses 1 */
-    if(meta.v4sum > hdr.udp.checksum) {
-        bit<16> tmp = 0xffff - meta.v4sum;
-        hdr.udp.checksum = hdr.udp.checksum + tmp;
-    } else {
-        hdr.udp.checksum = hdr.udp.checksum - meta.v4sum;
-    }
+    bit<16> tmp = ~hdr.udp.checksum;
+    tmp = tmp + meta.v6sum;
+    tmp = tmp - meta.v4sum;
+    hdr.udp.checksum = ~tmp;
 }
 
 action delta_tcp_from_v4_to_v6()
 {
     delta_prepare();
-    hdr.tcp.checksum = hdr.tcp.checksum + meta.v6sum;
 
-    /* prevent negative wrap around that loses 1 */
-    if(meta.v4sum > hdr.tcp.checksum) {
-        bit<16> tmp = 0xffff - meta.v4sum;
-        hdr.tcp.checksum = hdr.tcp.checksum + tmp;
-    } else {
-        hdr.tcp.checksum = hdr.tcp.checksum - meta.v4sum;
-    }
+    bit<16> tmp = ~hdr.tcp.checksum;
+    tmp = tmp + meta.v6sum;
+    tmp = tmp - meta.v4sum;
+    hdr.tcp.checksum = ~tmp;
 }
 
 action delta_ipv4_from_v6_to_v4()