diff --git a/packages/oas/src/converter/parts/postdata/BodyConverter.ts b/packages/oas/src/converter/parts/postdata/BodyConverter.ts
index a236d70f..1cf460d7 100644
--- a/packages/oas/src/converter/parts/postdata/BodyConverter.ts
+++ b/packages/oas/src/converter/parts/postdata/BodyConverter.ts
@@ -119,7 +119,9 @@ export abstract class BodyConverter<T extends OpenAPI.Document>
           this.inferContentType(val, propertySchema);
 
         const filenameRequired = this.filenameRequired(contentType);
-        const base64Encoded = this.BASE64_FORMATS.includes(schema?.format);
+        const base64Encoded = this.BASE64_FORMATS.includes(
+          propertySchema?.format
+        );
 
         const headers = [
           `Content-Disposition: form-data; name="${key}"${