diff -ur redshift-1.3/src/redshift.c redshift-1.3_reset/src/redshift.c
--- redshift-1.3/src/redshift.c	2010-05-06 15:29:54.000000000 -0700
+++ redshift-1.3_reset/src/redshift.c	2010-06-08 21:14:23.000000000 -0700
@@ -103,6 +103,7 @@
 #define DEFAULT_DAY_TEMP    5500
 #define DEFAULT_NIGHT_TEMP  3700
 #define DEFAULT_GAMMA        1.0
+#define RESET_TEMP          6500
 
 /* Angular elevation of the sun at which the color temperature
    transition period starts and ends (in degress).
@@ -276,7 +277,8 @@
 		"  -r\t\tDisable temperature transitions\n"
 		"  -s SCREEN\tX screen to apply adjustments to\n"
 		"  -c CRTC\tCRTC to apply adjustments to (RANDR only)\n"
-		"  -t DAY:NIGHT\tColor temperature to set at daytime/night\n"),
+		"  -t DAY:NIGHT\tColor temperature to set at daytime/night\n"
+		"  -x\t\tReset color temperature to default (same as -o -t 6500:6500)\n"),
 	      stdout);
 	fputs("\n", stdout);
 
@@ -320,11 +322,12 @@
 	int transition = 1;
 	int one_shot = 0;
 	int verbose = 0;
+	int reset = 0;
 	char *s;
 
 	/* Parse arguments. */
 	int opt;
-	while ((opt = getopt(argc, argv, "c:g:hl:m:ors:t:v")) != -1) {
+	while ((opt = getopt(argc, argv, "c:g:hl:m:ors:t:v:x")) != -1) {
 		switch (opt) {
 		case 'c':
 			crtc_num = atoi(optarg);
@@ -435,6 +438,9 @@
 		case 'v':
 			verbose = 1;
 			break;
+		case 'x':
+			reset = 1;
+			break;
 		case '?':
 			fputs(_("Try `-h' for more information.\n"), stderr);
 			exit(EXIT_FAILURE);
@@ -443,7 +449,7 @@
 	}
 
 	/* Latitude and longitude must be set */
-	if (isnan(lat) || isnan(lon)) {
+	if (!reset && (isnan(lat) || isnan(lon))) {
 		fputs(_("Latitude and longitude must be set.\n"), stderr);
 		fputs(_("Try `-h' for more information.\n"), stderr);
 		exit(EXIT_FAILURE);
@@ -455,7 +461,7 @@
 	}
 
 	/* Latitude */
-	if (lat < MIN_LAT || lat > MAX_LAT) {
+	if (!reset && (lat < MIN_LAT || lat > MAX_LAT)) {
 		/* TRANSLATORS: Append degree symbols if possible. */
 		fprintf(stderr,
 			_("Latitude must be between %.1f and %.1f.\n"),
@@ -464,7 +470,7 @@
 	}
 
 	/* Longitude */
-	if (lon < MIN_LON || lon > MAX_LON) {
+	if (!reset && (lon < MIN_LON || lon > MAX_LON)) {
 		/* TRANSLATORS: Append degree symbols if possible. */
 		fprintf(stderr,
 			_("Longitude must be between %.1f and %.1f.\n"),
@@ -602,6 +608,18 @@
 			gamma_state_free(&state, method);
 			exit(EXIT_FAILURE);
 		}
+	} else if (reset) {
+		int temp = RESET_TEMP;
+
+		if (verbose) printf(_("Color temperature: %uK\n"), temp);
+
+		/* Adjust temperature */
+		r = gamma_state_set_temperature(&state, method, temp, gamma);
+		if (r < 0) {
+			fputs(_("Temperature adjustment failed.\n"), stderr);
+			gamma_state_free(&state, method);
+			exit(EXIT_FAILURE);
+		}
 	} else {
 		/* Transition state */
 		double short_trans_end = 0;