diff --git a/libticker/src/ics/mod.rs b/libticker/src/ics/mod.rs
index 5b4c052..32cdca0 100644
--- a/libticker/src/ics/mod.rs
+++ b/libticker/src/ics/mod.rs
@@ -1,4 +1,5 @@
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
+use std::fmt::Write;
 use std::str::FromStr;
 use chrono::{NaiveDate, NaiveDateTime};
 
@@ -57,20 +58,28 @@ impl<'a> GetValue<'a, Timestamp> for Object {
     }
 }
 
-impl std::fmt::Display for Object {
-    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
-        writeln!(fmt, "BEGIN:{}", self.name)?;
+impl Object {
+    pub fn fmt_rrule(&self) -> Result<String, std::fmt::Error> {
+        let rrule_keys = [
+            "DTSTART",
+            "RRULE", "RDATE",
+            "EXRULE", "EXDATE",
+        ].iter().cloned().collect::<HashSet<_>>();
+
+        let mut s = String::new();
         for (name, values) in &self.content {
+            if ! rrule_keys.contains(name.as_str()) {
+                continue;
+            }
             for (props, value) in values {
-                write!(fmt, "{}", name)?;
+                write!(s, "{}", name)?;
                 for (key, prop) in props {
-                    write!(fmt, ";{}={}", key, prop)?;
+                    write!(s, ";{}={}", key, prop)?;
                 }
-                writeln!(fmt, ":{}", value)?;
+                writeln!(s, ":{}", value)?;
             }
         }
-        writeln!(fmt, "END:{}", self.name)?;
-        Ok(())
+        Ok(s)
     }
 }
 
diff --git a/ticker-update/src/main.rs b/ticker-update/src/main.rs
index 648cbbe..42368ef 100644
--- a/ticker-update/src/main.rs
+++ b/ticker-update/src/main.rs
@@ -63,7 +63,7 @@ fn obj_to_events(calendar: String, obj: &Object) -> Vec<Event> {
         }
     };
 
-    match RRule::from_str(&format!("{}", obj)) {
+    match RRule::from_str(&obj.fmt_rrule().unwrap()) {
         Ok(rrule) => {
             let now = Utc::now();
             let start = now - Duration::days(RRULE_LOOKBACK);
@@ -75,8 +75,7 @@ fn obj_to_events(calendar: String, obj: &Object) -> Vec<Event> {
                 .map(|dtstart| generate_event(dtstart, true))
                 .collect()
         }
-        Err(e) => {
-            println!("Error parsing RRULE: {}", e);
+        Err(_) => {
             vec![generate_event(dtstart, false)]
         }
     }