diff --git a/addons/xterm-addon-image/src/ImageStorage.ts b/addons/xterm-addon-image/src/ImageStorage.ts
index 86d48a6d..2fb12c14 100644
--- a/addons/xterm-addon-image/src/ImageStorage.ts
+++ b/addons/xterm-addon-image/src/ImageStorage.ts
@@ -56,7 +56,7 @@ class ExtendedAttrsImage implements IExtendedAttrsImage {
   public get underlineVarinatOffset(): number {
     const val = (this._ext & ExtFlags.VARIANT_OFFSET) >> 29;
     if (val < 0) {
-      return val ^ 4294967288;
+      return val ^ 0xFFFFFFF8;
     }
     return val;
   }