diff --git a/.gitignore b/.gitignore
index 31d985dd..da178fab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,4 @@ module-name-conflicts.txt
 /inclusive
 *.stackage
 /haddock/
+/build-summary/
diff --git a/Stackage/Build.hs b/Stackage/Build.hs
index 7443fbdb..6742b100 100644
--- a/Stackage/Build.hs
+++ b/Stackage/Build.hs
@@ -100,6 +100,7 @@ build settings' bp = do
                  : "--build-log=logs/$pkg.log"
                  : "--max-backjumps=-1"
                  : "--reorder-goals"
+                 : "--build-summary=build-summary/$pkgid.report"
                  : packageList
         hPutStrLn handle ("cabal " ++ unwords (map (\s -> "'" ++ s ++ "'") args))
         runCabal args handle