diff --git a/.changeset/hungry-cars-hammer.md b/.changeset/hungry-cars-hammer.md
new file mode 100644
index 0000000..3b67c39
--- /dev/null
+++ b/.changeset/hungry-cars-hammer.md
@@ -0,0 +1,5 @@
+---
+"mdcast": patch
+---
+
+default code language code blocks
diff --git a/mdcast.config.ts b/mdcast.config.ts
index e8a1111..610fc7a 100644
--- a/mdcast.config.ts
+++ b/mdcast.config.ts
@@ -14,6 +14,7 @@ const config: MdCastConfigInput = {
     canonical_url_base: "https://www.franciscomoretti.com/blog",
     link_url_base: "https://www.franciscomoretti.com",
     image_url_base: "https://www.franciscomoretti.com",
+    default_lang: "typescript",
   },
   devto: {
     should_publish: true,
diff --git a/src/clients/markdown.ts b/src/clients/markdown.ts
index 2da7986..4fd88cf 100644
--- a/src/clients/markdown.ts
+++ b/src/clients/markdown.ts
@@ -95,6 +95,19 @@ class MarkdownClient {
           });
         }
       )
+      .use(
+        // Insert default lang in code blocks
+        () => (tree: Root) => {
+          visit(tree, (node: Nodes) => {
+            if (node.type === "code") {
+              if (!node.lang && this.config.default_lang) {
+                // Only insert default lang if it's not already set
+                node.lang = this.config.default_lang;
+              }
+            }
+          });
+        }
+      )
       .use(() => (tree: Root) => {
         // Remove frontmatter node from the tree
         const [frontmatterNode, ...restNodes]: RootContent[] = tree.children;
diff --git a/src/clients/medium.ts b/src/clients/medium.ts
index 4fa8cf9..7bd4ad4 100644
--- a/src/clients/medium.ts
+++ b/src/clients/medium.ts
@@ -130,7 +130,7 @@ class MediumClient {
             return;
 
           const className = codeNode.properties["className"];
-          let lang = "markdown"; // TODO: get default lang from config
+          let lang = undefined;
           if (className) {
             if (typeof className === "string") {
               lang = className.replace("language-", "");
@@ -143,7 +143,9 @@ class MediumClient {
               }
             }
           }
-
+          if (!lang) {
+            return;
+          }
           node.properties = {
             "data-code-block-mode": "2",
             "data-code-block-lang": lang,
diff --git a/src/config/schema.ts b/src/config/schema.ts
index eaf9fa1..96e47c9 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -72,6 +72,7 @@ const FrontMatterPropertiesSchema = z.object({
 
 const MarkdownConfigSchema = z.object({
   frontmatterProperties: FrontMatterPropertiesSchema.optional().default({}),
+  default_lang: z.string().optional().default(""),
   link_url_base: z.string().default(""),
   canonical_url_base: z.string().default(""),
   image_url_base: z.string().default(""),