diff --git a/src/requests/register.cr b/src/requests/register.cr
index cc83c11..ae1c250 100644
--- a/src/requests/register.cr
+++ b/src/requests/register.cr
@@ -36,6 +36,7 @@ class AuthD::Request
 
 			# In this case we should not accept its registration.
 			return Response::ErrorPasswordTooShort.new if @password.size < 20
+			return Response::ErrorPasswordTooLong.new  if @password.size > 100
 
 			uid = authd.new_uid
 			password = authd.hash_password @password
diff --git a/src/responses/errors.cr b/src/responses/errors.cr
index 2cf12c6..dd52e4d 100644
--- a/src/responses/errors.cr
+++ b/src/responses/errors.cr
@@ -96,4 +96,10 @@ class AuthD::Response
 		end
 	end
 	AuthD.responses << ErrorInvalidRenewKey
+
+	IPC::JSON.message ErrorPasswordTooLong, 35 do
+		def initialize()
+		end
+	end
+	AuthD.responses << ErrorPasswordTooLong
 end