diff --git a/src/PIL/DdsImagePlugin.py b/src/PIL/DdsImagePlugin.py
index 65d9deaa0d4..812a1aeaaf4 100644
--- a/src/PIL/DdsImagePlugin.py
+++ b/src/PIL/DdsImagePlugin.py
@@ -155,7 +155,7 @@ def _open(self):
                 mask_count = 3
 
             masks = struct.unpack(
-                "<" + str(mask_count) + "I", header.read(mask_count * 4)
+                f"<{mask_count}I", header.read(mask_count * 4)
             )
             self.tile = [("dds_rgb", (0, 0) + self.size, 0, (bitcount, masks))]
         elif pfflags & DDPF_PALETTEINDEXED8: