diff --git a/cli/src/build.ts b/cli/src/build.ts
index 6ac79586..1cfc33c0 100644
--- a/cli/src/build.ts
+++ b/cli/src/build.ts
@@ -592,7 +592,11 @@ async function processIntermediateTypeFile(
           })
           break
         case 'impl':
-          impls.set(def.name, `${def.js_doc}${def.def}`)
+          const existed = impls.get(def.name)
+          impls.set(
+            def.name,
+            `${existed ? existed + '\n' : ''}${def.js_doc}${def.def}`,
+          )
           break
         case 'interface':
           dts +=
diff --git a/examples/napi/__test__/typegen.spec.ts.md b/examples/napi/__test__/typegen.spec.ts.md
index 30492b9a..a1ef7ede 100644
--- a/examples/napi/__test__/typegen.spec.ts.md
+++ b/examples/napi/__test__/typegen.spec.ts.md
@@ -217,6 +217,7 @@ Generated by [AVA](https://avajs.dev).
     export type Blake2bHasher = Blake2BHasher␊
     /** Smoking test for type generation */␊
     export class Blake2BHasher {␊
+      static withKey(key: Blake2bKey): Blake2BHasher␊
       update(data: Buffer): void␊
     }␊
     export type Blake2bKey = Blake2BKey␊
diff --git a/examples/napi/__test__/typegen.spec.ts.snap b/examples/napi/__test__/typegen.spec.ts.snap
index 00747f19..2fedede7 100644
Binary files a/examples/napi/__test__/typegen.spec.ts.snap and b/examples/napi/__test__/typegen.spec.ts.snap differ
diff --git a/examples/napi/index.d.ts b/examples/napi/index.d.ts
index 909980ed..12fdd1a9 100644
--- a/examples/napi/index.d.ts
+++ b/examples/napi/index.d.ts
@@ -207,6 +207,7 @@ export class Bird {
 export type Blake2bHasher = Blake2BHasher
 /** Smoking test for type generation */
 export class Blake2BHasher {
+  static withKey(key: Blake2bKey): Blake2BHasher
   update(data: Buffer): void
 }
 export type Blake2bKey = Blake2BKey