diff --git a/tools/datafileBuilder.py b/tools/datafileBuilder.py
index e5eb2ccf..c24ae5e1 100755
--- a/tools/datafileBuilder.py
+++ b/tools/datafileBuilder.py
@@ -14,7 +14,7 @@ parser.add_argument('--file', type=argparse.FileType('r'))
 parser.add_argument('--defaultType', type=str, choices=[t.name for t in list(dataType)])
 parser.add_argument('--format',type=str, choices=[t.name for t in list(Format)],default=Format.LINE.name)
 parser.add_argument('--debug', action='store_true', help='Debug mode')
-parser.add_argument('--prefix',type=str,default=None)
+parser.add_argument('--suffix',type=str,default=None)
 args = parser.parse_args()
 print(args)
 lines=args.file.readlines()
@@ -29,4 +29,4 @@ if not datapath.exists():
   datapath.mkdir()
 datalst=dataFileBase.readFromTable(dat,format=Format[args.format],default=dataType[args.defaultType],commands=commands)
 for data in datalst:
-  data.toFile(datapath,args.prefix)
\ No newline at end of file
+  data.toFile(datapath,args.suffix)
\ No newline at end of file
diff --git a/tools/lib/data.py b/tools/lib/data.py
index a9d8c6d6..df5631f6 100644
--- a/tools/lib/data.py
+++ b/tools/lib/data.py
@@ -326,7 +326,7 @@ class dataFileBase(object):
     dic["DOI"]="" if self.DOI is None else self.DOI
     return dic
   
-  def toFile(self,datadir,prefix=None):
+  def toFile(self,datadir,suffix=None):
     subpath=datadir/self.GetFileType().name.lower()
     if not subpath.exists():
       subpath.mkdir()
@@ -337,8 +337,8 @@ class dataFileBase(object):
     fileNameComp=[molfilename,self.method.name]
     if self.method.basis:
       fileNameComp.append(self.method.basis)
-    if prefix:
-      fileNameComp.append(prefix)
+    if suffix:
+      fileNameComp.append(suffix)
     fileName="_".join(fileNameComp)+".dat"
     file=subpath/fileName
     if not file.exists():