diff --git a/CHANGELOG b/CHANGELOG
index 2b2823d998..2ce4f60831 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,8 @@ git-annex (10.20250606) UNRELEASED; urgency=medium
 
   * Skip and warn when a tree import includes empty filenames,
     which can happen with eg a S3 bucket.
+  * Avoid a problem with temp file names ending in whitespace on
+    filesystems like VFAT that don't support such filenames.
 
  -- Joey Hess <id@joeyh.name>  Mon, 23 Jun 2025 11:11:29 -0400
 
diff --git a/Utility/Tmp.hs b/Utility/Tmp.hs
index f8be5b29c0..f373ca6c1c 100644
--- a/Utility/Tmp.hs
+++ b/Utility/Tmp.hs
@@ -117,13 +117,15 @@ relatedTemplate' :: RawFilePath -> RawFilePath
 relatedTemplate' f
 	| len > templateAddedLength = 
 		{- Some filesystems like FAT have issues with filenames
-		 - ending in ".", so avoid truncating a filename to end
-		 - that way. -}
-		B.dropWhileEnd (== dot) $
+		 - ending in ".", and others like VFAT don't allow a
+		 - filename to end with trailing whitespace, so avoid
+		 - truncating a filename to end that way. -}
+		B.dropWhileEnd disallowed $
 			truncateFilePath (len - templateAddedLength) f
 	| otherwise = f
   where
 	len = B.length f
+	disallowed c = c == dot || isSpace (chr (fromIntegral c))
 	dot = fromIntegral (ord '.')
 #else
 -- Avoids a test suite failure on windows, reason unknown, but
diff --git a/doc/bugs/openTempfile_invalid_argument_on_sd_card.mdwn b/doc/bugs/openTempfile_invalid_argument_on_sd_card.mdwn
index f3c37c5327..2763ae3a17 100644
--- a/doc/bugs/openTempfile_invalid_argument_on_sd_card.mdwn
+++ b/doc/bugs/openTempfile_invalid_argument_on_sd_card.mdwn
@@ -43,3 +43,5 @@ failed
 ### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
 
 I use it quite successfully to archive media on removable spinning hard drives.
+
+> [[fixed|done]] --[[Joey]]