diff --git a/tabxlsx.py b/tabxlsx.py
index ab5eec3..ac7c064 100755
--- a/tabxlsx.py
+++ b/tabxlsx.py
@@ -814,7 +814,6 @@ def extension(filename: str) -> Optional[str]:
     showheaders: List[str] = []
     sortheaders: List[str] = []
     for header in headers:
-        combines = ""
         for selheader in header.split("|"):
             if "@" in selheader:
                 selcol, rename = selheader.split("@", 1)
@@ -834,7 +833,6 @@ def extension(filename: str) -> Optional[str]:
     renaming: Dict[str, str] = {}
     selcols: List[str] = []
     for selecheader in selected:
-        combines = ""
         for selec in selecheader.split("|"):
             if "@" in selec:
                 selcol, rename = selec.split("@", 1)