diff --git a/part10/ElmHub.elm b/part10/ElmHub.elm
index cd5c201..edde01e 100644
--- a/part10/ElmHub.elm
+++ b/part10/ElmHub.elm
@@ -168,7 +168,7 @@ view model =
         ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->
diff --git a/part11/ElmHub.elm b/part11/ElmHub.elm
index 509f601..c1341a6 100644
--- a/part11/ElmHub.elm
+++ b/part11/ElmHub.elm
@@ -210,7 +210,7 @@ view model =
             ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->
diff --git a/part12/ElmHub.elm b/part12/ElmHub.elm
index 1d3ff29..4d9d1eb 100644
--- a/part12/ElmHub.elm
+++ b/part12/ElmHub.elm
@@ -250,7 +250,7 @@ view model =
         ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->
diff --git a/part13/ElmHub.elm b/part13/ElmHub.elm
index f15fadc..8897fdd 100644
--- a/part13/ElmHub.elm
+++ b/part13/ElmHub.elm
@@ -237,7 +237,7 @@ view model =
         ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->
diff --git a/part7/Main.elm b/part7/Main.elm
index beaff6c..557c122 100644
--- a/part7/Main.elm
+++ b/part7/Main.elm
@@ -95,7 +95,7 @@ view model =
         ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html Msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->
diff --git a/part8/Main.elm b/part8/Main.elm
index 3e4fd9f..1f26acb 100644
--- a/part8/Main.elm
+++ b/part8/Main.elm
@@ -79,7 +79,7 @@ view model =
         ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html Msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->
diff --git a/part9/ElmHub.elm b/part9/ElmHub.elm
index 32de441..87f3b17 100644
--- a/part9/ElmHub.elm
+++ b/part9/ElmHub.elm
@@ -77,7 +77,7 @@ view model =
         ]
 
 
-viewErrorMessage : Maybe String -> Html a
+viewErrorMessage : Maybe String -> Html msg
 viewErrorMessage errorMessage =
     case errorMessage of
         Just message ->