diff --git a/inputs.cc b/inputs.cc
index 6d207dc..45bd0c5 100644
--- a/inputs.cc
+++ b/inputs.cc
@@ -1008,9 +1008,10 @@ int LoadPAT(char *filename)
 			LR.antenna_pattern[x][y] = az * elevation;
 		}
 	}
+	return 0;
 }
 
-void LoadSignalColors(struct site xmtr)
+int LoadSignalColors(struct site xmtr)
 {
 	int x, y, ok, val[4];
 	char filename[255], string[80], *pointer = NULL, *s = NULL;
@@ -1095,14 +1096,13 @@ void LoadSignalColors(struct site xmtr)
 
 	region.levels = 13;
 
-	fd = fopen(filename, "r");
-
-	if (fd == NULL && xmtr.filename[0] == '\0')
-		/* Don't save if we don't have an output file */
-		return;
+	/* Don't save if we don't have an output file */
+	if ( xmtr.filename[0] == '\0' && (fd = fopen(filename, "r")) == NULL )
+		return 0;
 
 	if (fd == NULL) {
-		fd = fopen(filename, "w");
+		if( (fd = fopen(filename, "w")) == NULL )
+			return errno;
 
 		for (x = 0; x < region.levels; x++)
 			fprintf(fd, "%3d: %3d, %3d, %3d\n", region.level[x],
@@ -1147,6 +1147,7 @@ void LoadSignalColors(struct site xmtr)
 		fclose(fd);
 		region.levels = x;
 	}
+	return 0;
 }
 
 void LoadLossColors(struct site xmtr)
diff --git a/inputs.hh b/inputs.hh
index e634737..3f66472 100644
--- a/inputs.hh
+++ b/inputs.hh
@@ -6,7 +6,7 @@
 int LoadSDF_SDF(char *name, int winfiles);
 char LoadSDF(char *name, int winfiles);
 int LoadPAT(char *filename);
-void LoadSignalColors(struct site xmtr);
+int LoadSignalColors(struct site xmtr);
 void LoadLossColors(struct site xmtr);
 void LoadDBMColors(struct site xmtr);
 void LoadTopoData(int max_lon, int min_lon, int max_lat, int min_lat);
diff --git a/main.cc b/main.cc
index 74c4a6f..dfc62a8 100644
--- a/main.cc
+++ b/main.cc
@@ -1846,8 +1846,8 @@ int main(int argc, char *argv[])
 				DoRxdPwr((to_stdout == true ? NULL : mapfile), geo, kml, ngs, tx_site,
 					 txsites);
 			else
-				DoSigStr(mapfile, geo, kml, ngs, tx_site,
-					 txsites);
+				if( (result = DoSigStr(mapfile, geo, kml, ngs, tx_site,txsites)) != 0 )
+					return result;
 		}
 		if(lidar){
 			east=eastoffset;
diff --git a/outputs.cc b/outputs.cc
index ce2ba75..7f59063 100644
--- a/outputs.cc
+++ b/outputs.cc
@@ -256,7 +256,7 @@ void DoPathLoss(char *filename, unsigned char geo, unsigned char kml,
 
 }
 
-void DoSigStr(char *filename, unsigned char geo, unsigned char kml,
+int DoSigStr(char *filename, unsigned char geo, unsigned char kml,
 	      unsigned char ngs, struct site *xmtr, unsigned char txsites)
 {
 	/* This function generates a topographic map in Portable Pix Map
@@ -284,7 +284,10 @@ void DoSigStr(char *filename, unsigned char geo, unsigned char kml,
 	    255.0 / pow((double)(max_elevation - min_elevation),
 			one_over_gamma);
 
-	LoadSignalColors(xmtr[0]);
+	if( (success = LoadSignalColors(xmtr[0])) != 0 ){
+		fprintf(stderr,"Error loading signal colors\n");
+		return success;
+	}
 
 	if( filename != NULL ) {
 
diff --git a/outputs.hh b/outputs.hh
index ac334e4..2506292 100644
--- a/outputs.hh
+++ b/outputs.hh
@@ -3,7 +3,7 @@
 
 void DoPathLoss(char *filename, unsigned char geo, unsigned char kml,
 		unsigned char ngs, struct site *xmtr, unsigned char txsites);
-void DoSigStr(char *filename, unsigned char geo, unsigned char kml,
+int DoSigStr(char *filename, unsigned char geo, unsigned char kml,
 	      unsigned char ngs, struct site *xmtr, unsigned char txsites);
 void DoRxdPwr(char *filename, unsigned char geo, unsigned char kml,
 	      unsigned char ngs, struct site *xmtr, unsigned char txsites);