diff --git a/src/Mod/Import/CMakeLists.txt b/src/Mod/Import/CMakeLists.txt
index 2e7713840e..b29261b327 100644
--- a/src/Mod/Import/CMakeLists.txt
+++ b/src/Mod/Import/CMakeLists.txt
@@ -42,7 +42,6 @@ SET(DXF_Plate
 
 set(Import_Scripts
     Init.py
-    gzip_utf8.py
     stepZ.py
 )
 
diff --git a/src/Mod/Import/gzip_utf8.py b/src/Mod/Import/gzip_utf8.py
deleted file mode 100644
index 7a99852861..0000000000
--- a/src/Mod/Import/gzip_utf8.py
+++ /dev/null
@@ -1,530 +0,0 @@
-"""Functions that read and write gzipped files.
-
-The user of the file doesn't have to worry about the compression,
-but random access is not allowed."""
-
-# based on Andrew Kuchling's minigzip.py distributed with the zlib module
-
-# License: PSF, see https://www.python.org/psf/
-# original file: gzip.py from https://www.python.org/ftp/python/2.7.8/Python-2.7.8.tgz
-# changed line:
-# self.fileobj.write(fname + '\000')
-# to:
-# self.fileobj.write(fname.encode('utf-8') + '\000')
-# as a workaround to gzip filenames containing utf-8 characters on win systems 
-
-import struct, sys, time, os
-import zlib
-import io
-from __builtin__ import open as builtin_open
-try:
-    long
-except NameError:
-    long = int
-
-__all__ = ["GzipFile","open"]
-
-FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16
-
-READ, WRITE = 1, 2
-
-def write32u(output, value):
-    # The L format writes the bit pattern correctly whether signed
-    # or unsigned.
-    output.write(struct.pack("<L", value))
-
-def read32(input):
-    return struct.unpack("<I", input.read(4))[0]
-
-def open(filename, mode="rb", compresslevel=9):
-    """Shorthand for GzipFile(filename, mode, compresslevel).
-
-    The filename argument is required; mode defaults to 'rb'
-    and compresslevel defaults to 9.
-
-    """
-    return GzipFile(filename, mode, compresslevel)
-
-class GzipFile(io.BufferedIOBase):
-    """The GzipFile class simulates most of the methods of a file object with
-    the exception of the readinto() and truncate() methods.
-
-    """
-
-    myfileobj = None
-    max_read_chunk = 10 * 1024 * 1024   # 10Mb
-
-    def __init__(self, filename=None, mode=None,
-                 compresslevel=9, fileobj=None, mtime=None):
-        """Constructor for the GzipFile class.
-
-        At least one of fileobj and filename must be given a
-        non-trivial value.
-
-        The new class instance is based on fileobj, which can be a regular
-        file, a StringIO object, or any other object which simulates a file.
-        It defaults to None, in which case filename is opened to provide
-        a file object.
-
-        When fileobj is not None, the filename argument is only used to be
-        included in the gzip file header, which may includes the original
-        filename of the uncompressed file.  It defaults to the filename of
-        fileobj, if discernible; otherwise, it defaults to the empty string,
-        and in this case the original filename is not included in the header.
-
-        The mode argument can be any of 'r', 'rb', 'a', 'ab', 'w', or 'wb',
-        depending on whether the file will be read or written.  The default
-        is the mode of fileobj if discernible; otherwise, the default is 'rb'.
-        Be aware that only the 'rb', 'ab', and 'wb' values should be used
-        for cross-platform portability.
-
-        The compresslevel argument is an integer from 0 to 9 controlling the
-        level of compression; 1 is fastest and produces the least compression,
-        and 9 is slowest and produces the most compression. 0 is no compression
-        at all. The default is 9.
-
-        The mtime argument is an optional numeric timestamp to be written
-        to the stream when compressing.  All gzip compressed streams
-        are required to contain a timestamp.  If omitted or None, the
-        current time is used.  This module ignores the timestamp when
-        decompressing; however, some programs, such as gunzip, make use
-        of it.  The format of the timestamp is the same as that of the
-        return value of time.time() and of the st_mtime member of the
-        object returned by os.stat().
-
-        """
-
-        # Make sure we don't inadvertently enable universal newlines on the
-        # underlying file object - in read mode, this causes data corruption.
-        if mode:
-            mode = mode.replace('U', '')
-        # guarantee the file is opened in binary mode on platforms
-        # that care about that sort of thing
-        if mode and 'b' not in mode:
-            mode += 'b'
-        if fileobj is None:
-            fileobj = self.myfileobj = builtin_open(filename, mode or 'rb')
-        if filename is None:
-            # Issue #13781: os.fdopen() creates a fileobj with a bogus name
-            # attribute. Avoid saving this in the gzip header's filename field.
-            if hasattr(fileobj, 'name') and fileobj.name != '<fdopen>':
-                filename = fileobj.name
-            else:
-                filename = ''
-        if mode is None:
-            if hasattr(fileobj, 'mode'): mode = fileobj.mode
-            else: mode = 'rb'
-
-        if mode[0:1] == 'r':
-            self.mode = READ
-            # Set flag indicating start of a new member
-            self._new_member = True
-            # Buffer data read from gzip file. extrastart is offset in
-            # stream where buffer starts. extrasize is number of
-            # bytes remaining in buffer from current stream position.
-            self.extrabuf = ""
-            self.extrasize = 0
-            self.extrastart = 0
-            self.name = filename
-            # Starts small, scales exponentially
-            self.min_readsize = 100
-
-        elif mode[0:1] == 'w' or mode[0:1] == 'a':
-            self.mode = WRITE
-            self._init_write(filename)
-            self.compress = zlib.compressobj(compresslevel,
-                                             zlib.DEFLATED,
-                                             -zlib.MAX_WBITS,
-                                             zlib.DEF_MEM_LEVEL,
-                                             0)
-        else:
-            raise IOError( "Mode " + mode + " not supported" )
-
-        self.fileobj = fileobj
-        self.offset = 0
-        self.mtime = mtime
-
-        if self.mode == WRITE:
-            self._write_gzip_header()
-
-    @property
-    def filename(self):
-        import warnings
-        warnings.warn("use the name attribute", DeprecationWarning, 2)
-        if self.mode == WRITE and self.name[-3:] != ".gz":
-            return self.name + ".gz"
-        return self.name
-
-    def __repr__(self):
-        s = repr(self.fileobj)
-        return '<gzip ' + s[1:-1] + ' ' + hex(id(self)) + '>'
-
-    def _check_closed(self):
-        """Raises a ValueError if the underlying file object has been closed.
-
-        """
-        if self.closed:
-            raise ValueError('I/O operation on closed file.')
-
-    def _init_write(self, filename):
-        self.name = filename
-        self.crc = zlib.crc32(b"") & 0xffffffff
-        self.size = 0
-        self.writebuf = []
-        self.bufsize = 0
-
-    def _write_gzip_header(self):
-        self.fileobj.write('\037\213')             # magic header
-        self.fileobj.write('\010')                 # compression method
-        fname = os.path.basename(self.name)
-        if fname.endswith(".gz"):
-            fname = fname[:-3]
-        flags = 0
-        if fname:
-            flags = FNAME
-        self.fileobj.write(chr(flags))
-        mtime = self.mtime
-        if mtime is None:
-            mtime = time.time()
-        write32u(self.fileobj, long(mtime))
-        self.fileobj.write('\002')
-        self.fileobj.write('\377')
-        if fname:
-            self.fileobj.write(fname.encode('utf-8') + '\000')
-
-    def _init_read(self):
-        self.crc = zlib.crc32(b"") & 0xffffffff
-        self.size = 0
-
-    def _read_gzip_header(self):
-        magic = self.fileobj.read(2)
-        if magic != '\037\213':
-            raise IOError('Not a gzipped file')
-        method = ord( self.fileobj.read(1) )
-        if method != 8:
-            raise IOError('Unknown compression method')
-        flag = ord( self.fileobj.read(1) )
-        self.mtime = read32(self.fileobj)
-        # extraflag = self.fileobj.read(1)
-        # os = self.fileobj.read(1)
-        self.fileobj.read(2)
-
-        if flag & FEXTRA:
-            # Read & discard the extra field, if present
-            xlen = ord(self.fileobj.read(1))
-            xlen = xlen + 256*ord(self.fileobj.read(1))
-            self.fileobj.read(xlen)
-        if flag & FNAME:
-            # Read and discard a null-terminated string containing the filename
-            while True:
-                s = self.fileobj.read(1)
-                if not s or s=='\000':
-                    break
-        if flag & FCOMMENT:
-            # Read and discard a null-terminated string containing a comment
-            while True:
-                s = self.fileobj.read(1)
-                if not s or s=='\000':
-                    break
-        if flag & FHCRC:
-            self.fileobj.read(2)     # Read & discard the 16-bit header CRC
-
-    def write(self,data):
-        self._check_closed()
-        if self.mode != WRITE:
-            import errno
-            raise IOError(errno.EBADF, "write() on read-only GzipFile object")
-
-        if self.fileobj is None:
-            raise ValueError("write() on closed GzipFile object")
-
-        # Convert data type if called by io.BufferedWriter.
-        if isinstance(data, memoryview):
-            data = data.tobytes()
-
-        if len(data) > 0:
-            self.size = self.size + len(data)
-            self.crc = zlib.crc32(data, self.crc) & 0xffffffff
-            self.fileobj.write( self.compress.compress(data) )
-            self.offset += len(data)
-
-        return len(data)
-
-    def read(self, size=-1):
-        self._check_closed()
-        if self.mode != READ:
-            import errno
-            raise IOError(errno.EBADF, "read() on write-only GzipFile object")
-
-        if self.extrasize <= 0 and self.fileobj is None:
-            return ''
-
-        readsize = 1024
-        if size < 0:        # get the whole thing
-            try:
-                while True:
-                    self._read(readsize)
-                    readsize = min(self.max_read_chunk, readsize * 2)
-            except EOFError:
-                size = self.extrasize
-        else:               # just get some more of it
-            try:
-                while size > self.extrasize:
-                    self._read(readsize)
-                    readsize = min(self.max_read_chunk, readsize * 2)
-            except EOFError:
-                if size > self.extrasize:
-                    size = self.extrasize
-
-        offset = self.offset - self.extrastart
-        chunk = self.extrabuf[offset: offset + size]
-        self.extrasize = self.extrasize - size
-
-        self.offset += size
-        return chunk
-
-    def _unread(self, buf):
-        self.extrasize = len(buf) + self.extrasize
-        self.offset -= len(buf)
-
-    def _read(self, size=1024):
-        if self.fileobj is None:
-            raise EOFError("Reached EOF")
-
-        if self._new_member:
-            # If the _new_member flag is set, we have to
-            # jump to the next member, if there is one.
-            #
-            # First, check if we're at the end of the file;
-            # if so, it's time to stop; no more members to read.
-            pos = self.fileobj.tell()   # Save current position
-            self.fileobj.seek(0, 2)     # Seek to end of file
-            if pos == self.fileobj.tell():
-                raise EOFError("Reached EOF")
-            else:
-                self.fileobj.seek( pos ) # Return to original position
-
-            self._init_read()
-            self._read_gzip_header()
-            self.decompress = zlib.decompressobj(-zlib.MAX_WBITS)
-            self._new_member = False
-
-        # Read a chunk of data from the file
-        buf = self.fileobj.read(size)
-
-        # If the EOF has been reached, flush the decompression object
-        # and mark this object as finished.
-
-        if buf == "":
-            uncompress = self.decompress.flush()
-            self._read_eof()
-            self._add_read_data( uncompress )
-            raise EOFError('Reached EOF')
-
-        uncompress = self.decompress.decompress(buf)
-        self._add_read_data( uncompress )
-
-        if self.decompress.unused_data != "":
-            # Ending case: we've come to the end of a member in the file,
-            # so seek back to the start of the unused data, finish up
-            # this member, and read a new gzip header.
-            # (The number of bytes to seek back is the length of the unused
-            # data, minus 8 because _read_eof() will rewind a further 8 bytes)
-            self.fileobj.seek( -len(self.decompress.unused_data)+8, 1)
-
-            # Check the CRC and file size, and set the flag so we read
-            # a new member on the next call
-            self._read_eof()
-            self._new_member = True
-
-    def _add_read_data(self, data):
-        self.crc = zlib.crc32(data, self.crc) & 0xffffffff
-        offset = self.offset - self.extrastart
-        self.extrabuf = self.extrabuf[offset:] + data
-        self.extrasize = self.extrasize + len(data)
-        self.extrastart = self.offset
-        self.size = self.size + len(data)
-
-    def _read_eof(self):
-        # We've read to the end of the file, so we have to rewind in order
-        # to reread the 8 bytes containing the CRC and the file size.
-        # We check the that the computed CRC and size of the
-        # uncompressed data matches the stored values.  Note that the size
-        # stored is the true file size mod 2**32.
-        self.fileobj.seek(-8, 1)
-        crc32 = read32(self.fileobj)
-        isize = read32(self.fileobj)  # may exceed 2GB
-        if crc32 != self.crc:
-            raise IOError("CRC check failed %s != %s" % (hex(crc32),
-                                                         hex(self.crc)))
-        elif isize != (self.size & 0xffffffff):
-            raise IOError("Incorrect length of data produced")
-
-        # Gzip files can be padded with zeroes and still have archives.
-        # Consume all zero bytes and set the file position to the first
-        # non-zero byte. See http://www.gzip.org/#faq8
-        c = "\x00"
-        while c == "\x00":
-            c = self.fileobj.read(1)
-        if c:
-            self.fileobj.seek(-1, 1)
-
-    @property
-    def closed(self):
-        return self.fileobj is None
-
-    def close(self):
-        if self.fileobj is None:
-            return
-        if self.mode == WRITE:
-            self.fileobj.write(self.compress.flush())
-            write32u(self.fileobj, self.crc)
-            # self.size may exceed 2GB, or even 4GB
-            write32u(self.fileobj, self.size & 0xffffffff)
-            self.fileobj = None
-        elif self.mode == READ:
-            self.fileobj = None
-        if self.myfileobj:
-            self.myfileobj.close()
-            self.myfileobj = None
-
-    def flush(self,zlib_mode=zlib.Z_SYNC_FLUSH):
-        self._check_closed()
-        if self.mode == WRITE:
-            # Ensure the compressor's buffer is flushed
-            self.fileobj.write(self.compress.flush(zlib_mode))
-            self.fileobj.flush()
-
-    def fileno(self):
-        """Invoke the underlying file object's fileno() method.
-
-        This will raise AttributeError if the underlying file object
-        doesn't support fileno().
-        """
-        return self.fileobj.fileno()
-
-    def rewind(self):
-        '''Return the uncompressed stream file position indicator to the
-        beginning of the file'''
-        if self.mode != READ:
-            raise IOError("Can't rewind in write mode")
-        self.fileobj.seek(0)
-        self._new_member = True
-        self.extrabuf = ""
-        self.extrasize = 0
-        self.extrastart = 0
-        self.offset = 0
-
-    def readable(self):
-        return self.mode == READ
-
-    def writable(self):
-        return self.mode == WRITE
-
-    def seekable(self):
-        return True
-
-    def seek(self, offset, whence=0):
-        if whence:
-            if whence == 1:
-                offset = self.offset + offset
-            else:
-                raise ValueError('Seek from end not supported')
-        if self.mode == WRITE:
-            if offset < self.offset:
-                raise IOError('Negative seek in write mode')
-            count = offset - self.offset
-            for i in xrange(count // 1024):
-                self.write(1024 * '\0')
-            self.write((count % 1024) * '\0')
-        elif self.mode == READ:
-            if offset < self.offset:
-                # for negative seek, rewind and do positive seek
-                self.rewind()
-            count = offset - self.offset
-            for i in xrange(count // 1024):
-                self.read(1024)
-            self.read(count % 1024)
-
-        return self.offset
-
-    def readline(self, size=-1):
-        if size < 0:
-            # Shortcut common case - newline found in buffer.
-            offset = self.offset - self.extrastart
-            i = self.extrabuf.find('\n', offset) + 1
-            if i > 0:
-                self.extrasize -= i - offset
-                self.offset += i - offset
-                return self.extrabuf[offset: i]
-
-            size = sys.maxint
-            readsize = self.min_readsize
-        else:
-            readsize = size
-        bufs = []
-        while size != 0:
-            c = self.read(readsize)
-            i = c.find('\n')
-
-            # We set i=size to break out of the loop under two
-            # conditions: 1) there's no newline, and the chunk is
-            # larger than size, or 2) there is a newline, but the
-            # resulting line would be longer than 'size'.
-            if (size <= i) or (i == -1 and len(c) > size):
-                i = size - 1
-
-            if i >= 0 or c == '':
-                bufs.append(c[:i + 1])    # Add portion of last chunk
-                self._unread(c[i + 1:])   # Push back rest of chunk
-                break
-
-            # Append chunk to list, decrease 'size',
-            bufs.append(c)
-            size = size - len(c)
-            readsize = min(size, readsize * 2)
-        if readsize > self.min_readsize:
-            self.min_readsize = min(readsize, self.min_readsize * 2, 512)
-        return ''.join(bufs) # Return resulting line
-
-
-def _test():
-    # Act like gzip; with -d, act like gunzip.
-    # The input file is not deleted, however, nor are any other gzip
-    # options or features supported.
-    args = sys.argv[1:]
-    decompress = args and args[0] == "-d"
-    if decompress:
-        args = args[1:]
-    if not args:
-        args = ["-"]
-    for arg in args:
-        if decompress:
-            if arg == "-":
-                f = GzipFile(filename="", mode="rb", fileobj=sys.stdin)
-                g = sys.stdout
-            else:
-                if arg[-3:] != ".gz":
-                    print("filename doesn't end in .gz:", repr(arg))
-                    continue
-                f = open(arg, "rb")
-                g = builtin_open(arg[:-3], "wb")
-        else:
-            if arg == "-":
-                f = sys.stdin
-                g = GzipFile(filename="", mode="wb", fileobj=sys.stdout)
-            else:
-                f = builtin_open(arg, "rb")
-                g = open(arg + ".gz", "wb")
-        while True:
-            chunk = f.read(1024)
-            if not chunk:
-                break
-            g.write(chunk)
-        if g is not sys.stdout:
-            g.close()
-        if f is not sys.stdin:
-            f.close()
-
-if __name__ == '__main__':
-    _test()
diff --git a/src/Mod/Import/stepZ.py b/src/Mod/Import/stepZ.py
index a6f0034a02..19f7e5482f 100644
--- a/src/Mod/Import/stepZ.py
+++ b/src/Mod/Import/stepZ.py
@@ -27,13 +27,11 @@ ___stpZversion___ = "1.3.9"
 # Catia seems to use gz, Inventor zipfile
 # improved import, open and export
 
-if six.PY3:
-    import gzip as gz
-    import builtins as builtin  #py3
-    import importlib
-else:  # six.PY2
-    import gzip_utf8 as gz
-    import __builtin__ as builtin #py2
+
+import gzip as gz
+import builtins as builtin  #py3
+import importlib
+
 
 import zipfile  as zf
 
@@ -41,32 +39,19 @@ import zipfile  as zf
 # import stepZ; import importlib; importlib.reload(stepZ); import gzip_utf8; importlib.reload(gzip_utf8)
 
 def mkz_string(input):
-    if six.PY3:
-        if isinstance(input, str):
-            return input
-        else:
-            input = input.encode('utf-8')
-            return input
-    else:  # six.PY2
-        if isinstance(input, six.text_type):
-            input = input.encode('utf-8')
-            return input
-        else:
-            return input
+    if isinstance(input, str):
+        return input
+    else:
+        input = input.encode('utf-8')
+        return input
 ####
 def mkz_unicode(input):
-    if six.PY3:
-        if isinstance(input, str):
-            return input
-        else:
-            input = input.decode('utf-8')
-            return input
-    else:  # six.PY2
-        if isinstance(input, six.text_type):
-            input = input.decode('utf-8')
-            return input
-        else:
-            return input
+    if isinstance(input, str):
+        return input
+    else:
+        input = input.decode('utf-8')
+        return input
+ 
 ####
 def sayz(msg):
     FreeCAD.Console.PrintMessage(msg)