diff --git a/src/parser/diary_sexp.rs b/src/parser/diary_sexp.rs
index ed528d1..1c60b1b 100644
--- a/src/parser/diary_sexp.rs
+++ b/src/parser/diary_sexp.rs
@@ -1,8 +1,19 @@
+use nom::bytes::complete::tag;
+use nom::character::complete::space0;
+
 use super::Context;
 use crate::error::Res;
+use crate::parser::util::get_consumed;
+use crate::parser::util::start_of_line;
 use crate::parser::DiarySexp;
 
 #[tracing::instrument(ret, level = "debug")]
 pub fn diary_sexp<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, DiarySexp<'s>> {
-    todo!()
+    start_of_line(context, input)?;
+    let (remaining, _leading_whitespace) = space0(input)?;
+    let (remaining, _clock) = tag("%%")(remaining)?;
+    let (remaining, _gap_whitespace) = space0(remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((remaining, DiarySexp { source }))
 }