diff --git a/Annex/Content.hs b/Annex/Content.hs
index 1713b5e12d..ba67a2f151 100644
--- a/Annex/Content.hs
+++ b/Annex/Content.hs
@@ -177,6 +177,7 @@ checkDiskSpace' adjustment key = do
 	r <- getConfig g "diskreserve" ""
 	let reserve = fromMaybe megabyte $ readSize dataUnits r
 	stats <- liftIO $ getFileSystemStats (gitAnnexDir g)
+	sanitycheck r stats
 	case (stats, keySize key) of
 		(Nothing, _) -> return ()
 		(_, Nothing) -> return ()
@@ -189,7 +190,17 @@ checkDiskSpace' adjustment key = do
 		needmorespace n = unlessM (Annex.getState Annex.force) $
 			error $ "not enough free space, need " ++ 
 				roughSize storageUnits True n ++
-				" more (use --force to override this check or adjust annex.diskreserve)"
+				" more" ++ forcemsg
+		forcemsg = " (use --force to override this check or adjust annex.diskreserve)"
+		sanitycheck r stats
+			| not (null r) && isNothing stats = do
+				unlessM (Annex.getState Annex.force) $
+					error $ "You have configured a diskreserve of "
+						++ r ++
+						" but disk space checking is not working"
+						++ forcemsg
+				return ()
+			| otherwise = return ()
 
 {- Moves a file into .git/annex/objects/
  -
diff --git a/Makefile b/Makefile
index c7e5e5e127..43d498f1c1 100644
--- a/Makefile
+++ b/Makefile
@@ -21,11 +21,13 @@ endif
 
 all: $(all)
 
+sources: $(sources)
+
 # Disables optimisation. Not for production use.
 fast: GHCFLAGS=-Wall $(IGNORE)
 fast: $(bins)
 
-Build/SysConfig.hs: configure.hs Build/TestConfig.hs
+Build/SysConfig.hs: configure.hs Build/TestConfig.hs Utility/StatFS.hs
 	$(GHCMAKE) configure
 	./configure
 
diff --git a/configure.hs b/configure.hs
index 3b3626dd22..772df3e38f 100644
--- a/configure.hs
+++ b/configure.hs
@@ -2,9 +2,11 @@
 
 import System.Directory
 import Data.List
+import Data.Maybe
 import System.Cmd.Utils
 
 import Build.TestConfig
+import Utility.StatFS
 
 tests :: [TestCase]
 tests =
@@ -21,6 +23,7 @@ tests =
 	, TestCase "wget" $ testCmd "wget" "wget --version >/dev/null"
 	, TestCase "bup" $ testCmd "bup" "bup --version >/dev/null"
 	, TestCase "gpg" $ testCmd "gpg" "gpg --version >/dev/null"
+	, TestCase "StatFS" testStatFS
 	] ++ shaTestCases [1, 256, 512, 224, 384]
 
 shaTestCases :: [Int] -> [TestCase]
@@ -63,6 +66,11 @@ getGitVersion = do
 	let version = last $ words $ head $ lines s
 	return $ Config "gitversion" (StringConfig version)
 
+testStatFS :: Test
+testStatFS = do
+	s <- getFileSystemStats "."
+	return $ Config "statfs_sane" $ BoolConfig $ isJust s
+
 {- Set up cabal file with version. -}
 cabalSetup :: IO ()
 cabalSetup = do
diff --git a/debian/changelog b/debian/changelog
index b8b0d7327e..2e9468d8c4 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,6 +1,9 @@
 git-annex (3.20120114) UNRELEASED; urgency=low
 
-  * Add a sanity check for bad StatFS results.
+  * Add a sanity check for bad StatFS results. On architectures
+    where StatFS does not currently work (s390, mips, powerpc, sparc),
+    this disables the diskreserve checking code, and attempting to
+    configure an annex.diskreserve will result in an error.
 
  -- Joey Hess <joeyh@debian.org>  Sat, 14 Jan 2012 17:12:04 -0400
 
diff --git a/git-annex.cabal b/git-annex.cabal
index 4aee161b6a..aaa773a3d1 100644
--- a/git-annex.cabal
+++ b/git-annex.cabal
@@ -1,5 +1,5 @@
 Name: git-annex
-Version: 3.20120113
+Version: 3.20120114
 Cabal-Version: >= 1.6
 License: GPL
 Maintainer: Joey Hess <joey@kitenet.net>