diff --git a/Happstack/Authenticate/Core.hs b/Happstack/Authenticate/Core.hs
--- a/Happstack/Authenticate/Core.hs
+++ b/Happstack/Authenticate/Core.hs
@@ -88,6 +88,7 @@
     , GetUserByUsername(..)
     , GetUserByUserId(..)
     , GetUserByEmail(..)
+    , GetUsersByEmail(..)
     , GetAuthenticateState(..)
     , getOrGenSharedSecret
     , Token(..)
@@ -584,6 +585,14 @@
     do us <- view users
        return $ getOne $ us @= email
 
+-- | find all 'Users' which match 'Email'
+--
+getUsersByEmail :: Email
+               -> Query AuthenticateState (Set User)
+getUsersByEmail email =
+    do us <- view users
+       return $ toSet $ us @= email
+
 -- | get the entire AuthenticateState value
 getAuthenticateState :: Query AuthenticateState AuthenticateState
 getAuthenticateState = ask
@@ -602,6 +611,7 @@
     , 'getUserByUsername
     , 'getUserByUserId
     , 'getUserByEmail
+    , 'getUsersByEmail
     , 'getAuthenticateState
     ]
 
diff --git a/happstack-authenticate.cabal b/happstack-authenticate.cabal
--- a/happstack-authenticate.cabal
+++ b/happstack-authenticate.cabal
@@ -1,5 +1,5 @@
 Name:                happstack-authenticate
-Version:             2.4.0.3
+Version:             2.4.1
 Synopsis:            Happstack Authentication Library
 Description:         A themeable authentication library with support for username+password and OpenId.
 Homepage:            http://www.happstack.com/
@@ -10,8 +10,8 @@
 Copyright:           2011-2015 SeeReason Partners, LLC
 Category:            Web
 Build-type:          Simple
-Cabal-version:       >=1.8
-tested-with:         GHC==8.0.1, GHC==8.2.2, GHC==8.4.1, GHC==8.6.5, GHC==8.8.1
+Cabal-version:       >=1.10
+tested-with:         GHC==8.0.1, GHC==8.2.2, GHC==8.4.1, GHC==8.6.5, GHC==8.8.3, GHC==8.10.1
 data-files:
   messages/core/en.msg
   messages/openid/error/en.msg
@@ -24,6 +24,7 @@
     location: https://github.com/Happstack/happstack-authenticate.git
 
 Library
+  Default-language:    Haskell2010
   Exposed-modules:     Happstack.Authenticate.Core
                        Happstack.Authenticate.Controller
                        Happstack.Authenticate.Route
@@ -43,9 +44,9 @@
 
   Build-depends:       base                         > 4     && < 5,
                        acid-state                   >= 0.6  && < 0.17,
-                       aeson                        (>= 0.4  && < 0.10) || (>= 0.11 && < 1.5),
+                       aeson                        (>= 0.4  && < 0.10) || (>= 0.11 && < 1.6),
                        authenticate                 == 1.3.*,
-                       base64-bytestring            >= 1.0  && < 1.1,
+                       base64-bytestring            >= 1.0  && < 1.3,
                        boomerang                    >= 1.4  && < 1.5,
                        bytestring                   >= 0.9  && < 0.11,
                        containers                   >= 0.4  && < 0.7,
@@ -71,7 +72,7 @@
                        text                         >= 0.11 && < 1.3,
                        time                         >= 1.2  && < 1.11,
                        userid                       >= 0.1  && < 0.2,
-                       random                       >= 1.0  && < 1.2,
+                       random                       >= 1.0  && < 1.3,
                        shakespeare                  >= 2.0  && < 2.1,
                        unordered-containers         == 0.2.*,
                        web-routes                   >= 0.26 && < 0.28,