diff --git a/crates/tinymist-world/src/compute.rs b/crates/tinymist-world/src/compute.rs
index 3ce870a4c..a02fed09c 100644
--- a/crates/tinymist-world/src/compute.rs
+++ b/crates/tinymist-world/src/compute.rs
@@ -61,6 +61,8 @@ pub trait WorldComputable<F: CompilerFeat>: std::any::Any + Send + Sync + Sized
     /// }
     ///
     /// impl WorldComputable<SystemCompilerFeat> for SystemFontsOnce {
+    ///     type Output = Self;
+    ///
     ///     fn compute(graph: &Arc<WorldComputeGraph<SystemCompilerFeat>>) -> Result<Self> {
     ///
     ///         Ok(Self {