diff --git a/services/web/frontend/js/features/source-editor/lezer-typst/typst.grammar b/services/web/frontend/js/features/source-editor/lezer-typst/typst.grammar
index 3ae665d4ed..4b0b52d027 100644
--- a/services/web/frontend/js/features/source-editor/lezer-typst/typst.grammar
+++ b/services/web/frontend/js/features/source-editor/lezer-typst/typst.grammar
@@ -31,7 +31,10 @@ item {
 // HeadingMark is produced by an external tokenizer that enforces the
 // start-of-line constraint and captures the "=+" prefix + trailing space.
 Heading { HeadingMark HeadingTitle }
-HeadingTitle { headingTitleItem* }
+// headingTitleItem+ (not *) so HeadingTitle is never empty: the generator
+// would otherwise produce a shift/reduce conflict on "*" after HeadingMark,
+// unable to tell if "*" starts a Strong inside the heading or at doc level.
+HeadingTitle { headingTitleItem+ }
 headingTitleItem {
   Strong | Emphasis | CodeExpr | InlineMath | RawInline | Label | Ref | HeadingText
 }