diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,8 @@
 # Changelog for depq
 
+## 0.4.1
+* add Foldable instance
+
 ## 0.4
 * Add test suite ( @HirotoShioi )
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,5 +1,8 @@
 # depq
 
+[![Hackage](https://img.shields.io/hackage/v/depq.svg?logo=haskell)](https://hackage.haskell.org/package/depq)
+[![depq](http://stackage.org/package/depq/badge/nightly)](http://stackage.org/nightly/package/depq)
+
 Double-ended priority queues
 
 This library provides a type for 'DEPQ's, along with functions for constructing and querying them. 
diff --git a/depq.cabal b/depq.cabal
--- a/depq.cabal
+++ b/depq.cabal
@@ -1,5 +1,5 @@
 name:           depq
-version:        0.4.0.0
+version:        0.4.1.0
 synopsis:       Double-ended priority queues
 description:    Double-ended priority queues, for efficient retrieval of minimum and maximum elements in ordered collections of items.
 homepage:       https://github.com/ocramz/depq
diff --git a/src/Data/DEPQ.hs b/src/Data/DEPQ.hs
--- a/src/Data/DEPQ.hs
+++ b/src/Data/DEPQ.hs
@@ -58,6 +58,9 @@
   , maxHeap :: P.IntPSQ (Down p) a
                      } deriving (Eq, Show)
 
+instance Foldable (DEPQ p) where
+  foldr f z (DEPQ mi _) = foldr f z mi
+
 instance (NFData p, NFData a) => NFData (DEPQ p a) where
   rnf (DEPQ mi ma) = rnf mi `seq` rnf ma