diff --git a/gmtsph-regional.sh b/gmtsph-regional.sh
index 0964275..a5d4730 100755
--- a/gmtsph-regional.sh
+++ b/gmtsph-regional.sh
@@ -91,7 +91,7 @@ else
 	MAP_LABEL_OFFSET=2.5p
 
 	if [[ $nocpt == 1 ]]; then
-		$cptfile = ${color}
+		cptfile=${color}
 	else
 		gmt grd2cpt ${data} -R${range} -C${color} -Z -D -M > $cptfile
 	fi