diff --git a/cabal-install/Distribution/Client/Sandbox.hs b/cabal-install/Distribution/Client/Sandbox.hs
index fc137d38f44..cdd9f2d8335 100644
--- a/cabal-install/Distribution/Client/Sandbox.hs
+++ b/cabal-install/Distribution/Client/Sandbox.hs
@@ -429,6 +429,10 @@ sandboxDeleteSource verbosity buildTreeRefs _sandboxFlags globalFlags = do
   withRemoveTimestamps sandboxDir $ do
     Index.removeBuildTreeRefs verbosity indexFile buildTreeRefs
 
+  notice verbosity $ "Note: 'sandbox delete-source' only deletes the" ++
+    "add-source record, but does not unregister the package " ++
+    "from the package DB.\n\nUse 'sandbox hc-pkg -- unregister' to do that."
+
 -- | Entry point for the 'cabal sandbox list-sources' command.
 sandboxListSources :: Verbosity -> SandboxFlags -> GlobalFlags
                       -> IO ()
diff --git a/cabal-install/Distribution/Client/Setup.hs b/cabal-install/Distribution/Client/Setup.hs
index 9301c2617af..f302ec7cf98 100644
--- a/cabal-install/Distribution/Client/Setup.hs
+++ b/cabal-install/Distribution/Client/Setup.hs
@@ -1397,7 +1397,7 @@ sandboxCommand = CommandUI {
        "Usage: " ++ pname ++ " sandbox init\n"
     ++ "   or: " ++ pname ++ " sandbox delete\n"
     ++ "   or: " ++ pname ++ " sandbox add-source  [PATHS]\n\n"
-    ++ "   or: " ++ pname ++ " sandbox hc-pkg      [ARGS]\n"
+    ++ "   or: " ++ pname ++ " sandbox hc-pkg      -- [ARGS]\n"
     ++ "   or: " ++ pname ++ " sandbox list-sources\n\n"
     ++ "Flags for sandbox:",