diff --git a/.changeset/fair-kangaroos-clean.md b/.changeset/fair-kangaroos-clean.md
new file mode 100644
index 0000000000..654b1f2f67
--- /dev/null
+++ b/.changeset/fair-kangaroos-clean.md
@@ -0,0 +1,5 @@
+---
+"@blitzjs/codemod": patch
+---
+
+Remove TypeScript type annotations from `next.config.js` (a JavaScript file) in the `upgrade-legacy` codemod.
diff --git a/packages/codemod/src/upgrade-legacy.ts b/packages/codemod/src/upgrade-legacy.ts
index 9844158424..88f409ec72 100644
--- a/packages/codemod/src/upgrade-legacy.ts
+++ b/packages/codemod/src/upgrade-legacy.ts
@@ -70,8 +70,12 @@ const upgradeLegacy = async () => {
 
       // Remove all typescript stuff
       let findTypes = program.find(j.TSType, (node) => node)
-      if (findTypes) {
-        findTypes.forEach((t) => j(t.parentPath).remove())
+      if (findTypes.length) {
+        findTypes.forEach((t) => {
+          if (t.name === "typeAnnotation") {
+            j(t.parentPath).remove()
+          }
+        })
       }
 
       let withBlitz = j.objectProperty(j.identifier("withBlitz"), j.identifier("withBlitz"))