diff --git a/doc/rst/source/grdfill.rst b/doc/rst/source/grdfill.rst
index 39e99d50e41..b4876c01595 100644
--- a/doc/rst/source/grdfill.rst
+++ b/doc/rst/source/grdfill.rst
@@ -16,6 +16,7 @@ Synopsis
 [ |-A|\ *mode*\ [*arg*] ]
 [ |-G|\ *outgrid* ]
 [ |-L|\ [**p**] ]
+[ |-N|\ *value* ]
 [ |SYN_OPT-R| ]
 [ |SYN_OPT-V| ]
 [ |SYN_OPT-f| ]
@@ -28,8 +29,8 @@ Description
 
 **grdfill** reads a grid that presumably has unfilled holes that the user
 wants to fill in some fashion.  Holes are identified by NaN values but
-this criteria can be changed.  There are several different algorithms that
-can be used to replace the hole values.  One of **-A** or **-L** is required.
+this criteria can be changed via **-N**.  There are several different algorithms that
+can be used to replace the hole values.  **Note**: One of **-A** or **-L** is required.
 
 Required Arguments
 ------------------
@@ -43,11 +44,11 @@ Optional Arguments
 .. _-A:
 
 **-A**\ *mode*\ [*arg*]
-    Specify the hole-filling algorithm to use.  Choose from **c** for constant
-    fill and append the constant value, **n** for nearest neighbor (and optionally
-    append a search radius in pixels [default radius is :math:`r^2 = \sqrt{X^2 + Y^2}`,
+    Specify the hole-filling algorithm to use.  Choose among **c** for constant
+    fill (and append the constant fill *value*), **n** for nearest neighbor (and optionally
+    append a search *radius* in pixels [default radius is :math:`r^2 = \sqrt{X^2 + Y^2}`,
     where (*X,Y*) are the node dimensions of the grid]), or
-    *s** for bicubic spline [NOT IMPLEMENTED YET].
+    *s** for bicubic spline (optionally append a *tension* parameter [no tension]).
 
 .. _-G:
 
@@ -57,7 +58,7 @@ Optional Arguments
 .. _-N:
 
 **-N**\ [*nodata*]
-    Sets the node value that identifies a point as a member of a hole [Default is NaN].
+    Sets the node value used to identify a point as a member of a hole [Default is NaN].
 
 .. |Add_-R| replace:: This defines the subregion to be cut out. |Add_-R_links|
 .. include:: explain_-R.rst_
diff --git a/src/grdfill.c b/src/grdfill.c
index 2b8bc7197be..cfb2d68ff77 100644
--- a/src/grdfill.c
+++ b/src/grdfill.c
@@ -58,6 +58,10 @@ struct GRDFILL_CTRL {
 		bool active;
 		unsigned int mode;	/* 0 = region, 1 = polygons */
 	} L;
+	struct GRDFILL_N {	/* -N<value> */
+		bool active;
+		float value;
+	} N;
 };
 
 static void *New_Ctrl (struct GMT_CTRL *GMT) {	/* Allocate and initialize a new control structure */
@@ -80,7 +84,7 @@ static void Free_Ctrl (struct GMT_CTRL *GMT, struct GRDFILL_CTRL *C) {	/* Deallo
 static int usage (struct GMTAPI_CTRL *API, int level) {
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
-	GMT_Message (API, GMT_TIME_NONE, "usage: %s <ingrid> [-A<mode><options>] [-G<outgrid>] [-L[p]]\n\t[%s] [%s] [%s] [%s]\n\n",
+	GMT_Message (API, GMT_TIME_NONE, "usage: %s <ingrid> [-A<mode><options>] [-G<outgrid>] [-L[p]] [-N<val>\n\t[%s] [%s] [%s] [%s]\n\n",
 		name, GMT_Rgeo_OPT, GMT_V_OPT, GMT_f_OPT, GMT_PAR_OPT);
 
 	if (level == GMT_SYNOPSIS) return (GMT_MODULE_SYNOPSIS);
@@ -97,6 +101,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	GMT_Message (API, GMT_TIME_NONE, "\t-L Just list the subregions w/e/s/n of each hole.\n");
 	GMT_Message (API, GMT_TIME_NONE, "\t   No grid fill takes place and -G is ignored.\n");
 	GMT_Message (API, GMT_TIME_NONE, "\t   Append p to write polygons corresponding to these regions.\n");
+	GMT_Message (API, GMT_TIME_NONE, "\t-N Set alternate node value to indicate a hole [Default are NaN-nodes].\n");
 	GMT_Option (API, "R,V,f,.");
 
 	return (GMT_MODULE_USAGE);
@@ -169,6 +174,16 @@ static int parse (struct GMT_CTRL *GMT, struct GRDFILL_CTRL *Ctrl, struct GMT_OP
 					Ctrl->L.mode = 1;
 				break;
 
+			case 'N':
+				Ctrl->N.active = true;
+				if (opt->arg[0] && !strchr ("Nn", opt->arg[0]))
+					Ctrl->N.value = (float) atof (opt->arg);
+				else {
+					GMT_Report (API, GMT_MSG_ERROR, "Option -N: No value (or NaN) given\n");
+					n_errors++;
+				}
+				break;
+
 			default:	/* Report bad options */
 				n_errors += gmt_default_error (GMT, opt->option);
 				break;
@@ -178,6 +193,7 @@ static int parse (struct GMT_CTRL *GMT, struct GRDFILL_CTRL *Ctrl, struct GMT_OP
 	n_errors += gmt_M_check_condition (GMT, !Ctrl->In.file, "Must specify input grid file\n");
 	n_errors += gmt_M_check_condition (GMT, !(Ctrl->A.active || Ctrl->L.active), "Must specify an algorithm with -A unless -L is used\n");
 	n_errors += gmt_M_check_condition (GMT, !(Ctrl->L.active || Ctrl->G.file), "Must specify output grid file\n");
+	n_errors += gmt_M_check_condition (GMT, !(Ctrl->A.active || Ctrl->L.active), "Must specify either -A or -L\n");
 
 	return (n_errors ? GMT_PARSE_ERROR : GMT_NOERROR);
 }
@@ -522,6 +538,14 @@ EXTERN_MSC int GMT_grdfill (void *V_API, int mode, void *args) {
 		Return (API->error);	/* Get all */
 	}
 
+	if (Ctrl->N.active) {	/* User wants a specific value to indicate a hole instead of NaN; replace those values with NaNs since that is what is expected below */
+		gmt_M_grd_loop (GMT, Grid, row, col, node) {	/* Loop over all grid nodes */
+			if (floatAlmostEqualZero (Grid->data[node], Ctrl->N.value))
+				Grid->data[node] = GMT->session.f_NaN;
+		}
+	}
+	/* Here any hole is identified as a patch of NaNs */
+
 	if (Ctrl->A.mode == ALG_NN) {	/* Do Eric Xu's NN algorithm and bail */
 		int64_t radius = lrint (Ctrl->A.value);
 		struct GMT_GRID *New = NULL;