diff --git a/src/grdcontour.c b/src/grdcontour.c
index 322b7601dac..2f0b766d8cf 100644
--- a/src/grdcontour.c
+++ b/src/grdcontour.c
@@ -30,7 +30,7 @@
 #define THIS_MODULE_MODERN_NAME	"grdcontour"
 #define THIS_MODULE_LIB		"core"
 #define THIS_MODULE_PURPOSE	"Make contour map using a grid"
-#define THIS_MODULE_KEYS	"<G{,AD)=t,CC(,DDD,>X},G?(=1@<G{,AD)=t,CC(,DD),G?(=1"
+#define THIS_MODULE_KEYS	"<G{,AD)=t,CC(,DDD,NC(,)>X},G?(=1@<G{,AD)=t,CC(,DD),NC(,),G?(=1"
 #define THIS_MODULE_NEEDS	"Jg"
 #define THIS_MODULE_OPTIONS "-BJKOPRUVXYbdfhlptxy" GMT_OPT("EMmc")