diff --git a/sunset-alarm b/sunset-alarm
index cec4bd4..ffcd222 100755
--- a/sunset-alarm
+++ b/sunset-alarm
@@ -32,18 +32,23 @@ while [ $# -gt 0 ]; do
         -m) MINUTES="$2"; shift 2 ;;
         -h) usage ;;
         --) shift; break ;;
-        *) echo "Error: unknown argument '$1'" >&2; usage ;;
+        *) echo "ERROR: unknown argument '$1'" >&2; usage ;;
     esac
 done
 
 # Validate inputs
 if [ -z "$MINUTES" ]; then
-    echo "Error: -m MINUTES is required." >&2
+    echo "ERROR: -m MINUTES is required." >&2
     usage
 fi
 
 if [ -z "$LATLONG" ] && [ -z "$SUNSET_TIME" ]; then
-    echo "Error: must specify either -l LAT:LONG or -t HH:MI." >&2
+    echo "ERROR: must specify either -l LAT:LONG or -t HH:MI." >&2
+    usage
+fi
+
+if [[ -n "$LATLONG" && "$LATLONG" != *":"* ]]; then
+    echo "ERROR: LAT:LONG is missing the colon." >&2
     usage
 fi
 
@@ -146,7 +151,7 @@ while true; do
             SUNSET_EPOCH=$(date -d "${TODAY} ${SUNSET_TIME}" +%s 2>/dev/null)
 
             if [ -z "$SUNSET_EPOCH" ]; then
-                echo "Error: could not parse time '${SUNSET_TIME}'." >&2
+                echo "ERROR: could not parse time '${SUNSET_TIME}'." >&2
                 sleep 60
                 continue
             fi