diff --git a/pgdl.cabal b/pgdl.cabal
--- a/pgdl.cabal
+++ b/pgdl.cabal
@@ -1,6 +1,6 @@
 
 name:                pgdl
-version:             10.4
+version:             10.5
 license:             PublicDomain
 license-file:        LICENSE
 author:              mingchuan
@@ -39,7 +39,7 @@
                        data-default,
                        tagsoup,
                        directory-listing-webpage-parser >= 0.1.1.0,
-                       brick >= 0.13 && < 0.15, vty, microlens,
+                       brick >= 0.13 && < 0.16, vty, microlens,
                        conduit, conduit-extra,
                        http-conduit, http-types, resourcet,
                        configurator >= 0.3,
diff --git a/src/DownloadInterface.hs b/src/DownloadInterface.hs
--- a/src/DownloadInterface.hs
+++ b/src/DownloadInterface.hs
@@ -118,6 +118,7 @@
             T.AppEvent de -> case de of
                 UpdateFinishedSize b -> M.continue (UserInput (DownloadState b) ed)
                 DownloadFinish -> M.continue (UserInput FinishedState ed)
+        appEvent _ _ = error "unknown event received in event loop. (DL interface)"
         theMap = A.attrMap V.defAttr [ (P.progressCompleteAttr, V.black `on` V.cyan)
                                      , (P.progressIncompleteAttr, V.black `on` V.white)
                                      , ("input box", V.black `on` V.blue)
diff --git a/src/Main.hs b/src/Main.hs
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -141,6 +141,7 @@
                     cond (Directory entry _) = keyword `isKeyWordOf` decodedName entry
                     isKeyWordOf a b = T.toCaseFold a `T.isInfixOf` T.toCaseFold b
                 M.continue $ SearchState (filterDList dlst cond) newEd
+        appEvent _ _ = error "unknown event received in event loop."
         theMap = A.attrMap V.defAttr [ (L.listAttr, V.white `on` V.black)
                                      , ("directory", V.black `on` V.magenta)
                                      , ("file", V.black `on` V.cyan)