diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 0.7.1.1
+
+* Fix bug with existing .haddock file collection
+
 ## 0.7.1
 
 * Add the `stats` command
diff --git a/Stackage/PerformBuild.hs b/Stackage/PerformBuild.hs
--- a/Stackage/PerformBuild.hs
+++ b/Stackage/PerformBuild.hs
@@ -195,7 +195,6 @@
     warningsVar <- newTVarIO id
     mutex <- newMVar ()
     env <- getEnvironment
-    haddockFiles <- newTVarIO mempty
 
     registeredPackages <- setupPackageDatabase
         (pbDatabase pb)
@@ -204,6 +203,9 @@
         (ppVersion <$> bpPackages pbPlan)
         (deletePreviousResults pb)
 
+    pbLog "Collecting existing .haddock files\n"
+    haddockFiles <- getHaddockFiles pb >>= newTVarIO
+
     forM_ packageMap $ \pi -> void $ async $ singleBuild pb registeredPackages
       SingleBuild
         { sbSem = sem
@@ -570,3 +572,23 @@
     forM_ [minBound..maxBound] $ \rt ->
     withPRPath pb rt name $ \fp ->
     void $ tryIO $ removeFile fp
+
+-- | Discover existing .haddock files in the docs directory
+getHaddockFiles :: PerformBuild -> IO (Map Text FilePath)
+getHaddockFiles pb =
+      runResourceT
+    $ sourceDirectory (pbDocDir pb)
+   $$ foldMapMC (liftIO . go)
+  where
+    go :: FilePath -> IO (Map Text FilePath)
+    go dir =
+        case simpleParse nameVerText of
+            Nothing -> return mempty
+            Just pi@(PackageIdentifier (PackageName name) _) -> do
+                let fp = dir </> fpFromString name <.> "haddock"
+                exists <- isFile fp
+                return $ if exists
+                    then singletonMap nameVerText fp
+                    else mempty
+      where
+        nameVerText = fpToText $ filename dir
diff --git a/stackage-curator.cabal b/stackage-curator.cabal
--- a/stackage-curator.cabal
+++ b/stackage-curator.cabal
@@ -1,5 +1,5 @@
 name:                stackage-curator
-version:             0.7.1
+version:             0.7.1.1
 synopsis:            Tools for curating Stackage bundles
 description:         Please see <http://www.stackage.org/package/stackage-curator> for a description and documentation.
 homepage:            https://github.com/fpco/stackage