diff --git a/yesod-core.cabal b/yesod-core.cabal
--- a/yesod-core.cabal
+++ b/yesod-core.cabal
@@ -1,5 +1,5 @@
 name:            yesod-core
-version:         1.2.0.1
+version:         1.2.0.2
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -87,6 +87,9 @@
                      Yesod.Core.Class.Breadcrumbs
                      Paths_yesod_core
     ghc-options:     -Wall
+    -- Following line added due to: https://github.com/yesodweb/yesod/issues/545
+    -- This looks like a GHC bug
+    extensions:      MultiParamTypeClasses
 
 test-suite tests
     type: exitcode-stdio-1.0