diff --git a/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java b/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java
index 4227ac8..d4b1f41 100644
--- a/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java
+++ b/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java
@@ -93,7 +93,7 @@
     @Path("/{aid}/images")
     @GET
     @Produces(MediaType.APPLICATION_JSON)
-    public HashMap getPageUrls(@PathParam("aid") Integer aid) {
+    public HashMap<Integer, String> getPageUrls(@PathParam("aid") Integer aid) {
         Animation animation = gallery.getAnimationByAid(aid);
         ArrayList<Page> pages = animation.getPages();
         HashMap<Integer, String> pageUrl = new HashMap<>();