diff --git a/bin/foamMonitor b/bin/foamMonitor
index e38545f00d4b5a7de02a7b3dfe763309b78a702b..8ae19858b0f16dfc7b05d9cb91f9af39007c4bfe 100755
--- a/bin/foamMonitor
+++ b/bin/foamMonitor
@@ -155,7 +155,7 @@ for field in $KEYS
 do
     i=$(expr $i + 1)
     PLOTLINE="\"$FILE\" using 1:${i} with lines title \"$field\""
-    if [[ $i -lt $NCOLS ]]
+    if [ $i -lt $NCOLS ]
     then
        PLOTLINE="$PLOTLINE, \\"
     fi