diff --git a/Formula/postgresql@9.5.rb b/Formula/postgresql@9.5.rb
index 2d7e74c65a5..e592019b333 100644
--- a/Formula/postgresql@9.5.rb
+++ b/Formula/postgresql@9.5.rb
@@ -18,6 +18,9 @@ class PostgresqlAT95 < Formula
 
   keg_only :versioned_formula
 
+  # https://www.postgresql.org/support/versioning/
+  deprecate! date: "2021-02-11", because: :unsupported
+
   depends_on "openssl@1.1"
   depends_on "readline"