diff --git a/editors/vscode/.gitignore b/editors/vscode/.gitignore
index 773dc5cc..45f94c8a 100644
--- a/editors/vscode/.gitignore
+++ b/editors/vscode/.gitignore
@@ -1,4 +1,4 @@
 /fusion-*.vsix
 /node_modules
 /out
-/src/parser.js
+/src/fucheck.js
diff --git a/editors/vscode/Makefile b/editors/vscode/Makefile
index 71e854be..bac8528a 100644
--- a/editors/vscode/Makefile
+++ b/editors/vscode/Makefile
@@ -3,10 +3,10 @@ VERSION = 3.1.2
 run: fusion-$(VERSION).vsix
 	'$(LOCALAPPDATA)\Programs\Microsoft VS Code\bin\code' --extensionDevelopmentPath=$(abspath .)
 
-fusion-$(VERSION).vsix: package.json fu-logo.png fu-file.svg language-configuration.json tsconfig.json syntaxes/fusion.tmLanguage.json src/extension.ts src/parser.js node_modules
+fusion-$(VERSION).vsix: package.json fu-logo.png fu-file.svg language-configuration.json tsconfig.json syntaxes/fusion.tmLanguage.json src/extension.ts src/fucheck.js node_modules
 	vsce package
 
-src/parser.js: ../../Lexer.fu ../../AST.fu ../../Parser.fu
+src/fucheck.js: ../../Lexer.fu ../../AST.fu ../../Parser.fu ../../Sema.fu
 	fut -o $@ $^
 
 node_modules: package.json
diff --git a/editors/vscode/src/extension.ts b/editors/vscode/src/extension.ts
index fa603134..ef42fa76 100644
--- a/editors/vscode/src/extension.ts
+++ b/editors/vscode/src/extension.ts
@@ -19,9 +19,9 @@
 // along with Fusion Transpiler.  If not, see http://www.gnu.org/licenses/
 
 import * as vscode from "vscode";
-import { FuParser, FuProgram, FuSystem, FuParserHost } from "./parser.js";
+import { FuParser, FuProgram, FuSystem, FuSema, FuSemaHost } from "./fucheck.js";
 
-class VsCodeHost extends FuParserHost
+class VsCodeHost extends FuSemaHost
 {
 	#system = FuSystem.new();
 	#diagnostics: vscode.Diagnostic[] = [];
@@ -43,6 +43,11 @@ class VsCodeHost extends FuParserHost
 		parser.program.system = this.#system;
 		const input = new TextEncoder().encode(document.getText());
 		parser.parse(document.fileName, input, input.length);
+		if (this.#diagnostics.length == 0) {
+			const sema = new FuSema();
+			sema.setHost(this);
+			sema.process(parser.program);
+		}
 		diagnosticCollection.set(document.uri, this.#diagnostics);
 	}
 }
diff --git a/editors/vscode/tsconfig.json b/editors/vscode/tsconfig.json
index eed00969..6c2b0f0f 100644
--- a/editors/vscode/tsconfig.json
+++ b/editors/vscode/tsconfig.json
@@ -1,7 +1,7 @@
 {
   "files": [
     "src/extension.ts",
-    "src/parser.js"
+    "src/fucheck.js"
   ],
   "compilerOptions": {
     "target": "es2021",