diff --git a/sgx_jmp.rb b/sgx_jmp.rb
index 442010706fc56f9a9893de8de1a0f41350fecd02..9622812ec8c16a4e56db063250aa856b6a7e69ff 100644
--- a/sgx_jmp.rb
+++ b/sgx_jmp.rb
@@ -904,7 +904,7 @@ Command.new(
 	}.then do |iq|
 		jid = iq.form.field("jid")&.value.to_s.strip
 		tel = iq.form.field("tel")&.value.to_s.strip
-		if jid !~ /\./
+		if jid !~ /\./ || jid =~ /\s/
 			Command.finish("The Jabber ID you entered was not valid.", type: :error)
 		elsif tel !~ /\A\+\d+\Z/
 			Command.finish("Invalid telephone number", type: :error)