diff --git a/pycatfile.py b/pycatfile.py
index c64b204..2a8eac0 100755
--- a/pycatfile.py
+++ b/pycatfile.py
@@ -1952,7 +1952,7 @@ def ReadFileHeaderDataWithContent(fp, listonly=False, uncompress=True, skipcheck
         return False
     fp.seek(len(delimiter), 1)
     newfcs = GetHeaderChecksum(
-        HeaderOut[:-2] + [fprejsoncontent], HeaderOut[-4].lower(), True, formatspecs)
+        HeaderOut[:-2], HeaderOut[-4].lower(), True, formatspecs)
     HeaderOut.append(fjsoncontent)
     if(fcs != newfcs and not skipchecksum):
         VerbosePrintOut("File Header Checksum Error with file " +
@@ -2127,7 +2127,7 @@ def ReadFileHeaderDataWithContentToArray(fp, listonly=False, contentasfile=True,
     fcs = HeaderOut[-2].lower()
     fccs = HeaderOut[-1].lower()
     newfcs = GetHeaderChecksum(
-        HeaderOut[:-2] + [fprejsoncontent], HeaderOut[-4].lower(), True, formatspecs)
+        HeaderOut[:-2], HeaderOut[-4].lower(), True, formatspecs)
     if(fcs != newfcs and not skipchecksum):
         VerbosePrintOut("File Header Checksum Error with file " +
                         fname + " at offset " + str(fheaderstart))
@@ -2311,7 +2311,7 @@ def ReadFileHeaderDataWithContentToList(fp, listonly=False, contentasfile=False,
     fcs = HeaderOut[-2].lower()
     fccs = HeaderOut[-1].lower()
     newfcs = GetHeaderChecksum(
-        HeaderOut[:-2] + [fprejsoncontent], HeaderOut[-4].lower(), True, formatspecs)
+        HeaderOut[:-2], HeaderOut[-4].lower(), True, formatspecs)
     if(fcs != newfcs and not skipchecksum):
         VerbosePrintOut("File Header Checksum Error with file " +
                         fname + " at offset " + str(fheaderstart))
@@ -2533,7 +2533,7 @@ def ReadFileDataWithContentToArray(fp, seekstart=0, seekend=0, listonly=False, c
                 VerbosePrintOut("'" + prefjsonchecksum + "' != " + "'" + prejsonfcs + "'")
                 return False
             prenewfcs = GetHeaderChecksum(
-                preheaderdata[:-2] + prefprejsoncontent, preheaderdata[-4].lower(), True, formatspecs)
+                preheaderdata[:-2], preheaderdata[-4].lower(), True, formatspecs)
             prefcs = preheaderdata[-2]
             if(prefcs != prenewfcs and not skipchecksum):
                 VVerbosePrintOut("File Header Checksum Error with file " +
@@ -3322,7 +3322,7 @@ def AppendFileHeaderWithContent(fp, filevalues=[], extradata=[], jsondata={}, fi
         extrasizestr = extrasizestr + \
             AppendNullBytes(extradata, formatspecs['format_delimiter'])
     extrasizelen = format(len(extrasizestr), 'x').lower()
-    tmpoutlen = len(filevalues) + len(extradata) + 12
+    tmpoutlen = len(filevalues) + len(extradata) + 11
     tmpoutlenhex = format(tmpoutlen, 'x').lower()
     tmpoutlist = filevalues
     fjsontype = "json"
@@ -3341,9 +3341,10 @@ def AppendFileHeaderWithContent(fp, filevalues=[], extradata=[], jsondata={}, fi
     tmpoutlist.append(fjsonsize)
     if(len(jsondata) > 0):
         tmpoutlist.append(checksumtype[2])
+        tmpoutlist.append(GetFileChecksum(fjsoncontent, checksumtype[2], True, formatspecs))
     else:
         tmpoutlist.append("none")
-    tmpoutlist.append(GetFileChecksum(fjsoncontent, checksumtype[2], True, formatspecs))
+        tmpoutlist.append(GetFileChecksum(fjsoncontent, "none", True, formatspecs))
     tmpoutlist.append(extrasizelen)
     tmpoutlist.append(extrafields)
     outfileoutstr = AppendNullBytes(
@@ -3359,7 +3360,7 @@ def AppendFileHeaderWithContent(fp, filevalues=[], extradata=[], jsondata={}, fi
         AppendNullBytes(checksumlist, formatspecs['format_delimiter'])
     nullstrecd = formatspecs['format_delimiter'].encode('UTF-8')
     outfileheadercshex = GetFileChecksum(
-        outfileoutstr + fjsoncontent + nullstrecd, checksumtype[0], True, formatspecs)
+        outfileoutstr, checksumtype[0], True, formatspecs)
     if(len(filecontent) == 0):
         outfilecontentcshex = GetFileChecksum(
             filecontent, "none", False, formatspecs)
@@ -3373,7 +3374,7 @@ def AppendFileHeaderWithContent(fp, filevalues=[], extradata=[], jsondata={}, fi
     outfileoutstr = AppendNullByte(
         formheaersize, formatspecs['format_delimiter']) + outfileoutstr
     outfileheadercshex = GetFileChecksum(
-        outfileoutstr + fjsoncontent + nullstrecd, checksumtype[0], True, formatspecs)
+        outfileoutstr, checksumtype[0], True, formatspecs)
     outfileoutstr = outfileoutstr + \
         AppendNullBytes([outfileheadercshex, outfilecontentcshex],
                         formatspecs['format_delimiter'])
@@ -6626,7 +6627,7 @@ def CatFileSeekToFileNum(infile, fmttype="auto", seekto=0, listonly=False, conte
             prefcs = preheaderdata[-2].lower()
             prenewfcs = preheaderdata[-1].lower()
             prenewfcs = GetHeaderChecksum(
-                preheaderdata[:-2] + [prefjoutfprejsoncontent], preheaderdata[-4].lower(), True, formatspecs)
+                preheaderdata[:-2], preheaderdata[-4].lower(), True, formatspecs)
             if(prefcs != prenewfcs and not skipchecksum):
                 VerbosePrintOut("File Header Checksum Error with file " +
                                 prefname + " at offset " + str(prefhstart))
@@ -6938,7 +6939,7 @@ def CatFileSeekToFileName(infile, fmttype="auto", seekfile=None, listonly=False,
             prefcs = preheaderdata[-2].lower()
             prenewfcs = preheaderdata[-1].lower()
             prenewfcs = GetHeaderChecksum(
-                preheaderdata[:-2] + [prefjoutfprejsoncontent], preheaderdata[-4].lower(), True, formatspecs)
+                preheaderdata[:-2], preheaderdata[-4].lower(), True, formatspecs)
             if(prefcs != prenewfcs and not skipchecksum):
                 VerbosePrintOut("File Header Checksum Error with file " +
                                 prefname + " at offset " + str(prefhstart))
@@ -7260,7 +7261,7 @@ def CatFileValidate(infile, fmttype="auto", formatspecs=__file_format_multi_dict
         outfcs = inheaderdata[-2].lower()
         outfccs = inheaderdata[-1].lower()
         infcs = GetHeaderChecksum(
-            inheaderdata[:-2] + [outfprejsoncontent], inheaderdata[-4].lower(), True, formatspecs)
+            inheaderdata[:-2], inheaderdata[-4].lower(), True, formatspecs)
         if(verbose):
             VerbosePrintOut(outfname)
             VerbosePrintOut("Record Number " + str(il) + "; File ID " +
@@ -7594,7 +7595,7 @@ def CatFileToArray(infile, fmttype="auto", seekstart=0, seekend=0, listonly=Fals
             prefcs = preheaderdata[-2].lower()
             prenewfcs = preheaderdata[-1].lower()
             prenewfcs = GetHeaderChecksum(
-                preheaderdata[:-2] + [prefjoutfprejsoncontent], preheaderdata[-4].lower(), True, formatspecs)
+                preheaderdata[:-2], preheaderdata[-4].lower(), True, formatspecs)
             if(prefcs != prenewfcs and not skipchecksum):
                 VerbosePrintOut("File Header Checksum Error with file " +
                                 prefname + " at offset " + str(prefhstart))
@@ -7753,7 +7754,7 @@ def CatFileToArray(infile, fmttype="auto", seekstart=0, seekend=0, listonly=Fals
         outfcs = inheaderdata[-2].lower()
         outfccs = inheaderdata[-1].lower()
         infcs = GetHeaderChecksum(
-            inheaderdata[:-2] + [outfprejsoncontent], inheaderdata[-4].lower(), True, formatspecs)
+            inheaderdata[:-2], inheaderdata[-4].lower(), True, formatspecs)
         if(outfcs != infcs and not skipchecksum):
             VerbosePrintOut("File Header Checksum Error with file " +
                             outfname + " at offset " + str(outfhstart))