diff --git a/code/exercises/src/Ex11/Exercise.hs b/code/exercises/src/Ex11/Exercise.hs
index 0eee581..49f2f09 100644
--- a/code/exercises/src/Ex11/Exercise.hs
+++ b/code/exercises/src/Ex11/Exercise.hs
@@ -6,6 +6,8 @@ module Ex11.Exercise where
 import Control.Monad.Fix (MonadFix)
 
 import Data.Text (Text)
+import qualified Data.Text as Text
+
 import qualified Data.Map as Map
 
 import Reflex
diff --git a/code/exercises/src/Ex12/Exercise.hs b/code/exercises/src/Ex12/Exercise.hs
index 832c610..21661e2 100644
--- a/code/exercises/src/Ex12/Exercise.hs
+++ b/code/exercises/src/Ex12/Exercise.hs
@@ -5,7 +5,11 @@ module Ex12.Exercise where
 
 import Control.Monad.Fix (MonadFix)
 
+import Control.Lens
+
 import Data.Text (Text)
+import qualified Data.Text as Text
+
 import qualified Data.Map as Map
 
 import Reflex
diff --git a/code/exercises/src/Ex13/Exercise.hs b/code/exercises/src/Ex13/Exercise.hs
index 6980524..33b9d12 100644
--- a/code/exercises/src/Ex13/Exercise.hs
+++ b/code/exercises/src/Ex13/Exercise.hs
@@ -6,6 +6,8 @@ module Ex13.Exercise where
 import Control.Monad.Fix (MonadFix)
 
 import Data.Text (Text)
+import qualified Data.Text as Text
+
 import qualified Data.Map as Map
 
 import Reflex
diff --git a/code/exercises/src/Ex14/Exercise.hs b/code/exercises/src/Ex14/Exercise.hs
index be932d2..35116f2 100644
--- a/code/exercises/src/Ex14/Exercise.hs
+++ b/code/exercises/src/Ex14/Exercise.hs
@@ -6,6 +6,8 @@ module Ex14.Exercise where
 import Control.Monad.Fix (MonadFix)
 
 import Data.Text (Text)
+import qualified Data.Text as Text
+
 import qualified Data.Map as Map
 
 import Reflex