diff --git a/aster-lsp/src/goto_def.rs b/aster-lsp/src/goto_def.rs
index f17a0e9..3df7c6f 100644
--- a/aster-lsp/src/goto_def.rs
+++ b/aster-lsp/src/goto_def.rs
@@ -41,14 +41,8 @@ pub fn handle_goto_definition(
         let location = Location {
             uri: uri.clone(),
             range: Range {
-                start: Position {
-                    line: l,
-                    character: c,
-                },
-                end: Position {
-                    line: l,
-                    character: c + word.len() as u32,
-                },
+                start: Position { line: l, character: c },
+                end: Position { line: l, character: c + word.len() as u32 },
             },
         };
         let response: GotoDefinitionResponse = GotoDefinitionResponse::Scalar(location);
diff --git a/aster-lsp/src/server.rs b/aster-lsp/src/server.rs
index b58b89a..c35fae1 100644
--- a/aster-lsp/src/server.rs
+++ b/aster-lsp/src/server.rs
@@ -28,7 +28,17 @@ pub fn run() {
         text_document_sync: Some(TextDocumentSyncCapability::Kind(
             TextDocumentSyncKind::FULL,
         )),
-        completion_provider: Some(lsp_types::CompletionOptions::default()),
+        completion_provider: Some(lsp_types::CompletionOptions {
+            trigger_characters: Some(
+                (b'a'..=b'z').chain(b'A'..=b'Z')
+                    .map(|c| (c as char).to_string())
+                    .chain(std::iter::once(".".to_string()))
+                    .chain(std::iter::once("_".to_string()))
+                    .collect()
+            ),
+            resolve_provider: Some(false),
+            ..Default::default()
+        }),
         hover_provider: Some(lsp_types::HoverProviderCapability::Simple(true)),
         signature_help_provider: Some(lsp_types::SignatureHelpOptions::default()),
         definition_provider: Some(lsp_types::OneOf::Left(true)),
diff --git a/vscode-ext/syntaxes/aster.tmLanguage.json b/vscode-ext/syntaxes/aster.tmLanguage.json
index 9d14ea4..679ba1a 100644
--- a/vscode-ext/syntaxes/aster.tmLanguage.json
+++ b/vscode-ext/syntaxes/aster.tmLanguage.json
@@ -84,7 +84,7 @@
             "patterns": [
                 {
                     "name": "keyword.control.aster",
-                    "match": "\\b(let|const|fn|if|else|while|for|in|break|continue|return)\\b"
+                    "match": "\\b(let|const|fn|if|else|while|for|in|break|continue|return|try|catch|finally|throw)\\b"
                 }
             ]
         },