diff --git a/imagesize/imagesize.py b/imagesize/imagesize.py
index e6ed07e..e9213b6 100644
--- a/imagesize/imagesize.py
+++ b/imagesize/imagesize.py
@@ -253,8 +253,8 @@ def get(filepath):
             if head[12:16] == b"VP8 ":
                 width, height = struct.unpack("<HH", head[26:30])
             elif head[12:16] == b"VP8X":
-                width = struct.unpack("<I", head[24:27] + b"\0")[0]
-                height = struct.unpack("<I", head[27:30] + b"\0")[0]
+                width = struct.unpack("<I", head[24:27] + b"\0")[0] + 1
+                height = struct.unpack("<I", head[27:30] + b"\0")[0] + 1
             elif head[12:16] == b"VP8L":
                 b = head[21:25]
                 width = (((b[1] & 63) << 8) | b[0]) + 1
diff --git a/test/images/test_vp8x.webp b/test/images/test_vp8x.webp
new file mode 100644
index 0000000..be7beae
Binary files /dev/null and b/test/images/test_vp8x.webp differ
diff --git a/test/test_get.py b/test/test_get.py
index d786296..45ccd2f 100644
--- a/test/test_get.py
+++ b/test/test_get.py
@@ -104,6 +104,16 @@ def test_littleendian_tiff_bytes(self):
         self.assertEqual(width, 800)
         self.assertEqual(height, 600)
 
+    def test_load_webp_vp8x(self):
+        """Test VP8X format WebP file parsing.
+        
+        VP8X format stores dimensions as (width-1, height-1) in the header,
+        so the parser must add 1 to get the actual dimensions.
+        """
+        width, height = imagesize.get(os.path.join(imagedir, "test_vp8x.webp"))
+        self.assertEqual(width, 200)
+        self.assertEqual(height, 1)
+
     @unittest.skipIf(Path is None, "requires pathlib support")
     def test_load_png_path(self):
         width, height = imagesize.get(Path(imagedir, "test.png"))