diff --git a/gmtsph-regional.sh b/gmtsph-regional.sh
index 112de62..247c376 100755
--- a/gmtsph-regional.sh
+++ b/gmtsph-regional.sh
@@ -91,7 +91,7 @@ else
 	MAP_GRID_PEN_PRIMARY=thinnest,grey,-- \
 	FONT_LABEL=8p,Times-Roman,black \
 	MAP_FRAME_AXES=WESnZ \
-	COLOR_NAN=black \
+	COLOR_NAN=white \
 	MAP_LABEL_OFFSET=2.5p
 
 	if [[ $nocpt == 1 ]]; then