diff --git a/hmemdb.cabal b/hmemdb.cabal
--- a/hmemdb.cabal
+++ b/hmemdb.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                hmemdb
-version:             0.3.1.0
+version:             0.3.1.1
 synopsis:            In-memory relational database
 description:         Library that provides a sort of relational database in memory (which could be saved to the disk, however). Very untested.
 license:             BSD3
diff --git a/src/Data/HMemDb.hs b/src/Data/HMemDb.hs
--- a/src/Data/HMemDb.hs
+++ b/src/Data/HMemDb.hs
@@ -63,7 +63,7 @@
     mToList = return . sVal
     mSingleton = Single
     mInsert _ _ = Nothing
-    mDelete n s = guard (n == sVal s) >> return s
+    mDelete n s = guard (n /= sVal s) >> return s
 instance Binary Multiple where
     get = fmap Multiple get
     put = put . mVal