diff --git a/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java b/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java
index 4cf6c47..b9c2bf2 100644
--- a/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java
+++ b/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java
@@ -4,6 +4,8 @@
 import android.content.SharedPreferences;
 import android.graphics.drawable.shapes.OvalShape;
 
+import androidx.core.math.MathUtils;
+
 import org.ntlab.acanthus_client.entities.Animation;
 import org.ntlab.acanthus_client.entities.AnimationJson;
 
@@ -134,7 +136,7 @@
     }
 
     public void setEditingPageNo(Integer editingPageNo) {
-        this.editingPageNo = editingPageNo;
+        this.editingPageNo = MathUtils.clamp(editingPageNo, 0, 999);
     }
 
     public void setCurrentAnimation(Animation currentAnimation) {