diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,10 @@
 # Revision history for `cabal-plan`
 
+## 0.1.1.0
+
+* Add `cabal-plan fingerprint` command for printing
+  sha256 sums of source tarballs
+
 ## 0.1.0.0
 
 * First version. Released on an unsuspecting world.
diff --git a/cabal-plan.cabal b/cabal-plan.cabal
--- a/cabal-plan.cabal
+++ b/cabal-plan.cabal
@@ -1,5 +1,5 @@
 name:                cabal-plan
-version:             0.1.0.0
+version:             0.1.1.0
 synopsis:            Library and utiltity for processing cabal's plan.json file
 homepage:            https://github.com/hvr/cabal-plan
 license:             GPL-3
@@ -10,6 +10,7 @@
 category:            Development
 build-type:          Simple
 cabal-version:       >=1.10
+tested-with: GHC==8.0.2, GHC==7.10.3, GHC==7.8.4, GHC==7.6.3
 description:
   This package provides a library for decoding @plan.json@ files as
   well as simple tool @cabal-plan@ for extracting and pretty printing
diff --git a/src-exe/cabal-plan.hs b/src-exe/cabal-plan.hs
--- a/src-exe/cabal-plan.hs
+++ b/src-exe/cabal-plan.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE OverloadedStrings #-}
 
 module Main where
 
@@ -10,6 +11,7 @@
 import           Data.Set                 (Set)
 import qualified Data.Set                 as S
 import qualified Data.Text                as T
+import qualified Data.Text.IO             as T
 import qualified Data.Text.Lazy           as LT
 import qualified Data.Text.Lazy.Builder   as LT
 import qualified Data.Text.Lazy.IO        as LT
@@ -27,7 +29,8 @@
       ("info":_) -> doInfo
       ("show":_) -> print =<< findAndDecodePlanJson
       ("list-bin":_) -> doListBin
-      _ -> fail "unknown command (known commands: info show list-bin)"
+      ("fingerprint":_) -> doFingerprint
+      _ -> fail "unknown command (known commands: info show list-bin fingerprint)"
 
 doListBin :: IO ()
 doListBin = do
@@ -43,6 +46,21 @@
                             CompNameLib -> T.unpack (pn <> T.pack":lib:" <> pn)
                             _           -> T.unpack (pn <> T.pack":" <> dispCompName cn)
                   putStrLn (g ++ "  " ++ fn)
+
+doFingerprint :: IO ()
+doFingerprint = do
+    (v,_projbase) <- findAndDecodePlanJson
+
+    let pids = M.fromList [ (uPId u, u) | (_,u) <- M.toList (pjUnits v) ]
+
+    forM_ (M.toList pids) $ \(_,Unit{..}) -> do
+        let h = maybe "________________________________________________________________"
+                      dispSha256 $ uSha256
+        case uType of
+          UnitTypeBuiltin -> T.putStrLn (h <> " B " <> dispPkgId uPId)
+          UnitTypeGlobal  -> T.putStrLn (h <> " G " <> dispPkgId uPId)
+          UnitTypeLocal   -> T.putStrLn (h <> " L " <> dispPkgId uPId)
+          UnitTypeInplace -> T.putStrLn (h <> " I " <> dispPkgId uPId)
 
 doInfo :: IO ()
 doInfo = do