diff --git a/Annex/AdjustedBranch.hs b/Annex/AdjustedBranch.hs
index 2baed04a0a..bebb5c77c2 100644
--- a/Annex/AdjustedBranch.hs
+++ b/Annex/AdjustedBranch.hs
@@ -160,21 +160,41 @@ originalBranch = fmap fromAdjustedBranch <$> inRepo Git.Branch.current
  - adjusted version of a branch, changes the adjustment of the original
  - branch).
  -
- - Can fail, if no branch is checked out, or perhaps if staged changes
- - conflict with the adjusted branch.
+ - Can fail, if no branch is checked out, or if the adjusted branch already
+ - exists, or perhaps if staged changes conflict with the adjusted branch.
  -}
-enterAdjustedBranch :: Adjustment -> Annex ()
+enterAdjustedBranch :: Adjustment -> Annex Bool
 enterAdjustedBranch adj = go =<< originalBranch
   where
 	go (Just origbranch) = do
-		AdjBranch b <- preventCommits $ const $ 
-			adjustBranch adj origbranch
-		showOutput -- checkout can have output in large repos
-		inRepo $ Git.Command.run
-			[ Param "checkout"
-			, Param $ fromRef $ Git.Ref.base b
-			]
-	go Nothing = error "not on any branch!"
+		let adjbranch = adjBranch $ originalToAdjusted origbranch adj
+		ifM (inRepo $ Git.Ref.exists adjbranch)
+			( do
+				mapM_ (warning . unwords)
+					[ [ "adjusted branch"
+					  , Git.Ref.describe adjbranch
+					  , "already exists."
+					  ]
+					, [ "Aborting because that branch may have changes that have not yet reached"
+					  , Git.Ref.describe origbranch
+					  ]
+					, [ "You can check out the adjusted branch manually to enter it,"
+					  , "or delete the adjusted branch and re-run this command."
+					  ]
+					]
+				return False
+			, do
+				AdjBranch b <- preventCommits $ const $ 
+					adjustBranch adj origbranch
+				showOutput -- checkout can have output in large repos
+				inRepo $ Git.Command.runBool
+					[ Param "checkout"
+					, Param $ fromRef $ Git.Ref.base b
+					]
+			)
+	go Nothing = do
+		warning "not on any branch!"
+		return False
 
 adjustToCrippledFileSystem :: Annex ()
 adjustToCrippledFileSystem = do
@@ -186,7 +206,8 @@ adjustToCrippledFileSystem = do
 			, Param "-m"
 			, Param "commit before entering adjusted unlocked branch"
 			]
-	enterAdjustedBranch UnlockAdjustment
+	unlessM (enterAdjustedBranch UnlockAdjustment) $
+		warning "Failed to enter adjusted branch!"
 
 setBasisBranch :: BasisBranch -> Ref -> Annex ()
 setBasisBranch (BasisBranch basis) new = 
diff --git a/Command/Adjust.hs b/Command/Adjust.hs
index addc652db5..8c62c144ca 100644
--- a/Command/Adjust.hs
+++ b/Command/Adjust.hs
@@ -35,5 +35,4 @@ start :: Adjustment -> CommandStart
 start adj = do
 	checkVersionSupported
 	showStart "adjust" ""
-	enterAdjustedBranch adj
-	next $ next $ return True
+	next $ next $ enterAdjustedBranch adj
diff --git a/debian/changelog b/debian/changelog
index 1c246ff97a..a653efdfd9 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -3,6 +3,9 @@ git-annex (6.20160512) UNRELEASED; urgency=medium
   * Change git annex info remote encryption description to use wording
     closer to what's used in initremote.
   * webapp: Avoid confusing display of dead remotes.
+  * adjust: If the adjusted branch already exists, avoid overwriting it,
+    since it might contain changes that have not yet been propigated to the
+    original branch.
 
  -- Joey Hess <id@joeyh.name>  Wed, 11 May 2016 16:08:38 -0400