diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index a7742e7af..2c742a6b1 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -2189,7 +2189,7 @@ class Image:
             filename = str(fp)
             open_fp = True
         elif isPath(fp):
-            filename = fp
+            filename = os.fsdecode(fp)
             open_fp = True
         elif fp == sys.stdout:
             try:
@@ -2209,7 +2209,7 @@ class Image:
 
         preinit()
 
-        ext = os.fsdecode(os.path.splitext(filename)[1].lower())
+        ext = os.path.splitext(filename)[1].lower()
 
         if not format:
             if ext not in EXTENSION:
diff --git a/src/PIL/Jpeg2KImagePlugin.py b/src/PIL/Jpeg2KImagePlugin.py
index 8e0ff0735..0904b241b 100644
--- a/src/PIL/Jpeg2KImagePlugin.py
+++ b/src/PIL/Jpeg2KImagePlugin.py
@@ -317,7 +317,7 @@ def _accept(prefix):
 
 
 def _save(im, fp, filename):
-    if os.fsdecode(os.path.splitext(filename)[1]) == ".j2k":
+    if filename.endswith(".j2k"):
         kind = "j2k"
     else:
         kind = "jp2"