diff --git a/bin/foamVTKSeries b/bin/foamVTKSeries
index c5c7370dea..b2414f0c87 100755
--- a/bin/foamVTKSeries
+++ b/bin/foamVTKSeries
@@ -123,8 +123,6 @@ do
     # Get the names of VTK files in this category
     names=$(for f in $subDir_files; do basename "$f" .vtk; done | sort -u)
 
-    unset comma
-
     for n in $names
     do
         # Create list of VTK files of a given name, ordered by time step
@@ -137,6 +135,8 @@ do
         series_file="$s/$n.vtk.series"
         seriesFileHead > "$series_file"
 
+        unset comma
+
         for f in $files
         do
             # Write series file