ext_priority = ['.zst','.xz','.bz2']
 
     for base, exts in dumpext.items():
-        found = False
-        if len(exts) == 1:
-            yield base + exts[0]
-            found = True
-        else:
-            for ext in ext_priority:
-                if ext in exts:
-                    yield base + ext
-                    found = True
-        assert(found == True)
+        ext = [ext for ext in ext_priority if ext in exts][0]
+        yield base + ext
 
 def open_fileset(files):
     for fh in files:
         cmd = ["xzcat",'-dk', '-T 20',input_filename]
     elif re.match(r'.*\.zst',input_filename):
         cmd = ['zstd','-dck', input_filename]
+    elif re.match(r'.*\.gz',input_filename):
+        cmd = ['gzip','-dc', input_filename]
     try:
         input_file = Popen(cmd, stdout=PIPE).stdout
     except NameError as e: