diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,13 @@
 
+90000.1.1
+=========
+
+Bug fixes:
+* The `EnableSignUpWithGitLab` field of `ClientConfig` is now optional
+  using `Maybe` since some servers do not provide it. Prior to this
+  change, the library would fail to decode the `ClientConfig` completely
+  if the field was missing.
+
 90000.1.0
 =========
 
diff --git a/mattermost-api.cabal b/mattermost-api.cabal
--- a/mattermost-api.cabal
+++ b/mattermost-api.cabal
@@ -1,5 +1,5 @@
 name:                mattermost-api
-version:             90000.1.0
+version:             90000.1.1
 synopsis:            Client API for Mattermost chat system
 
 description:         Client API for Mattermost chat system.  Mattermost is a
diff --git a/src/Network/Mattermost/Types/Config.hs b/src/Network/Mattermost/Types/Config.hs
--- a/src/Network/Mattermost/Types/Config.hs
+++ b/src/Network/Mattermost/Types/Config.hs
@@ -241,7 +241,7 @@
   , clientConfigRequireEmailVerification :: T.Text
   , clientConfigEnableEmailBatching :: T.Text
 
-  , clientConfigEnableSignUpWithGitLab :: T.Text
+  , clientConfigEnableSignUpWithGitLab :: Maybe T.Text
 
   , clientConfigShowEmailAddress :: T.Text
 
@@ -337,7 +337,7 @@
     clientConfigRequireEmailVerification <- o A..: "RequireEmailVerification"
     clientConfigEnableEmailBatching <- o A..: "EnableEmailBatching"
 
-    clientConfigEnableSignUpWithGitLab <- o A..: "EnableSignUpWithGitLab"
+    clientConfigEnableSignUpWithGitLab <- o A..:? "EnableSignUpWithGitLab"
 
     clientConfigShowEmailAddress <- o A..: "ShowEmailAddress"