diff --git a/invokeai/backend/image_util/imwatermark/vendor.py b/invokeai/backend/image_util/imwatermark/vendor.py
index ef06274ff73..f96aae54521 100644
--- a/invokeai/backend/image_util/imwatermark/vendor.py
+++ b/invokeai/backend/image_util/imwatermark/vendor.py
@@ -7,9 +7,9 @@
 # `opencv-contrib-python`. It's easier to copy the code over than complicate the installation process by
 # requiring an extra post-install step of removing `opencv-python` and installing `opencv-contrib-python`.
 
-import struct
-import uuid
 import base64
+import uuid
+
 import cv2
 import numpy as np
 import pywt
@@ -111,14 +111,12 @@ def __init__(self, wm_type="bytes", length=0):
             raise NameError("%s is unsupported" % wm_type)
 
     def reconstruct_ipv4(self, bits):
-        ips = [str(ip) for ip in list(np.packbits(bits))]
-        return ".".join(ips)
+        packed = np.packbits(bits)
+        return "{}.{}.{}.{}".format(packed[0], packed[1], packed[2], packed[3])
 
     def reconstruct_uuid(self, bits):
         nums = np.packbits(bits)
-        bstr = b""
-        for i in range(16):
-            bstr += struct.pack(">B", nums[i])
+        bstr = bytes(nums[:16])
 
         return str(uuid.UUID(bytes=bstr))
 
@@ -132,10 +130,10 @@ def reconstruct_b16(self, bits):
 
     def reconstruct_bytes(self, bits):
         nums = np.packbits(bits)
-        bstr = b""
-        for i in range(self._wmLen // 8):
-            bstr += struct.pack(">B", nums[i])
-        return bstr
+        # Equivalent to b''.join(struct.pack(">B", nums[i]) for i in range(self._wmLen // 8))
+        # Since all can be packed in one go:
+        end_idx = self._wmLen // 8
+        return bytes(nums[:end_idx])
 
     def reconstruct(self, bits):
         if len(bits) != self._wmLen: