diff --git a/src/extract.ts b/src/extract.ts
index ee01a9f..768fd51 100644
--- a/src/extract.ts
+++ b/src/extract.ts
@@ -100,6 +100,9 @@ function processDeclaration(declaration: string): string {
   else if (declaration.startsWith('export interface')) {
     return processInterfaceDeclaration(declaration)
   }
+  else if (declaration.startsWith('interface')) {
+    return processInterfaceDeclaration(declaration)
+  }
   else if (declaration.startsWith('export type')) {
     return processTypeDeclaration(declaration)
   }