diff --git a/package.json b/package.json
index b8f19ed..f0d6db3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@vscode/prompt-tsx",
-	"version": "0.3.0-alpha.9",
+	"version": "0.3.0-alpha.10",
 	"description": "Declare LLM prompts with TSX",
 	"main": "./dist/base/index.js",
 	"types": "./dist/base/index.d.ts",
diff --git a/src/base/tokenizer/tokenizer.ts b/src/base/tokenizer/tokenizer.ts
index a243029..9267159 100644
--- a/src/base/tokenizer/tokenizer.ts
+++ b/src/base/tokenizer/tokenizer.ts
@@ -36,7 +36,7 @@ export class AnyTokenizer implements ITokenizer {
 		const vscode = require('vscode');
 		return this.countTokens({
 			role: this.toChatRole(message.role),
-			content: vscode.LanguageModelTextPart(message.content),
+			content: new vscode.LanguageModelTextPart(message.content),
 			name: 'name' in message ? message.name : undefined,
 		});
 	}