diff --git a/crates/oq3_parser/src/grammar/expressions/atom.rs b/crates/oq3_parser/src/grammar/expressions/atom.rs
index aceb839..1a8252a 100644
--- a/crates/oq3_parser/src/grammar/expressions/atom.rs
+++ b/crates/oq3_parser/src/grammar/expressions/atom.rs
@@ -24,6 +24,9 @@ pub(crate) fn literal(p: &mut Parser<'_>) -> Option<CompletedMarker> {
     if !p.at_ts(LITERAL_FIRST) {
         return None;
     }
+    if p.at(STRING) {
+        p.error("Unexpected string literal");
+    }
     let m = p.start();
     p.bump_any();
     Some(m.complete(p, LITERAL))