diff --git a/internal.js b/internal.js
index 1da261d..54d5f59 100644
--- a/internal.js
+++ b/internal.js
@@ -14,9 +14,6 @@ var p7 = {
 
 
 (function() {
-  /* ---------------------Global variables--------------------- */
-  var checksumTries = 0;
-
   /* ---------------------Utilitaries--------------------- */
 
   /* Sum individual bytes 
@@ -56,36 +53,36 @@ var p7 = {
 
   /* Create a basic (Non-Extended) packet */
   /* Return the packet */
-  p7.make.basicPacket = (type, subtype) => p7.make.checksum([type]        //Type (T)
-                                          .concat(subtype.hexToAscii(2))  //Subtype (ST)
-                                          .concat([0x30]));               //Extended (EX)
+  p7.make.basicPacket = (type, subtype) => p7.make.checksum([type,   //Type (T)
+                                          ...subtype.hexToAscii(2),  //Subtype (ST)
+                                          0x30]);                    //Extended (EX)
 
   /* Create an extended command packet */
   /* Return the packet */
   p7.make.extendedCommandPacket = (subtype, datatype, fileSize, commandArguments) => {
-    let data =  [0x30, 0x30]                    //Overwrite (OW)
-                .concat([0x30, 0x30])           //Data type (DT) ??
-                .concat(fileSize.hexToAscii(8)) //File size (FS)
-                .concat(commandArguments.flatMap((element) => element.length.hexToAscii(2))) //Size of Data {1..6} (SD{1..6})
-                .concat(commandArguments.join('').toAscii());                                //Data {1..6} (D{1..6})
+    let data =  [0x30, 0x30,               //Overwrite (OW)
+                ...[0x30, 0x30],           //Data type (DT) ??
+                ...fileSize.hexToAscii(8), //File size (FS)
+                ...commandArguments.flatMap((element) => element.length.hexToAscii(2)), //Size of Data {1..6} (SD{1..6})
+                ...commandArguments.join('').toAscii()];                                //Data {1..6} (D{1..6})
     
-    return  p7.make.checksum([0x01]            //Type (T)
-            .concat(subtype.hexToAscii(2))     //Subtype (ST)
-            .concat([0x31])                    //Extended (EX)
-            .concat(data.length.hexToAscii(4)) //Data size (DS)
-            .concat(data));                    //Data (D)
+    return  p7.make.checksum([0x01,       //Type (T)
+            ...subtype.hexToAscii(2),     //Subtype (ST)
+            0x31,                         //Extended (EX)
+            ...data.length.hexToAscii(4), //Data size (DS)
+            ...data]);                    //Data (D)
   }
 
   /* Create a data packet */
   /* Return the packet */
   p7.make.dataPacket = (subtype, totalNumber, currentNumber, data) =>
-    p7.make.checksum([0x02]                            //Type field
-                  .concat(subtype.hexToAscii(2))       //Subtype (ST) field
-                  .concat([0x31])                      //Extended (EX) field
-                  .concat((data.length + 8 /* Total number (TN) and Current number (CN) subfields */ ).hexToAscii(4)) //Data size (DS) field
-                  .concat(totalNumber.hexToAscii(4))   //Total number (TN) subfield
-                  .concat(currentNumber.hexToAscii(4)) //Current number (CN) subfield
-                  .concat(data));                      //Data (DD) subfield
+    p7.make.checksum([0x02,             //Type field
+    ...subtype.hexToAscii(2),           //Subtype (ST) field
+    0x31,                               //Extended (EX) field
+    ...(data.length + 8).hexToAscii(4), //Data size (DS) field
+    ...totalNumber.hexToAscii(4),       //Total number (TN) subfield
+    ...currentNumber.hexToAscii(4),     //Current number (CN) subfield
+    ...data]);                          //Data (DD) subfield
 
 
   /* ---------------------Packet decoding--------------------- */
@@ -201,7 +198,6 @@ var p7 = {
     });
   }
 
-
   /* ---------------------Packet sending--------------------- */
 
   p7.send.packet = async function (buffer) {