diff --git a/nixos/tests/elk.nix b/nixos/tests/elk.nix
index 8488c97c01e8..fee350de65b5 100644
--- a/nixos/tests/elk.nix
+++ b/nixos/tests/elk.nix
@@ -120,6 +120,7 @@ let
           };
       };
 
+    passthru.elkPackages = elk;
     testScript = ''
       import json
 
diff --git a/pkgs/tools/misc/logstash/6.x.nix b/pkgs/tools/misc/logstash/6.x.nix
index 97ee5b2ed3f3..1c7ab29cbc86 100644
--- a/pkgs/tools/misc/logstash/6.x.nix
+++ b/pkgs/tools/misc/logstash/6.x.nix
@@ -3,12 +3,13 @@
 , lib, stdenv
 , fetchurl
 , makeWrapper
+, nixosTests
 , jre
 }:
 
 with lib;
 
-stdenv.mkDerivation rec {
+let this = stdenv.mkDerivation rec {
   version = elk6Version;
   name = "logstash-${optionalString (!enableUnfree) "oss-"}${version}";
 
@@ -52,4 +53,12 @@ stdenv.mkDerivation rec {
     platforms   = platforms.unix;
     maintainers = with maintainers; [ wjlroe offline basvandijk ];
   };
-}
+  passthru.tests =
+    optionalAttrs (!enableUnfree) (
+      assert this.drvPath == nixosTests.elk.ELK-6.elkPackages.logstash.drvPath;
+      {
+        elk = nixosTests.elk.ELK-6;
+      }
+    );
+};
+in this
diff --git a/pkgs/tools/misc/logstash/7.x.nix b/pkgs/tools/misc/logstash/7.x.nix
index 0817a7ab087e..1abc0ff9bf82 100644
--- a/pkgs/tools/misc/logstash/7.x.nix
+++ b/pkgs/tools/misc/logstash/7.x.nix
@@ -3,12 +3,13 @@
 , lib, stdenv
 , fetchurl
 , makeWrapper
+, nixosTests
 , jre
 }:
 
 with lib;
 
-stdenv.mkDerivation rec {
+let this = stdenv.mkDerivation rec {
   version = elk7Version;
   name = "logstash-${optionalString (!enableUnfree) "oss-"}${version}";
 
@@ -52,4 +53,12 @@ stdenv.mkDerivation rec {
     platforms   = platforms.unix;
     maintainers = with maintainers; [ wjlroe offline basvandijk ];
   };
-}
+  passthru.tests =
+    optionalAttrs (!enableUnfree) (
+      assert this.drvPath == nixosTests.elk.ELK-7.elkPackages.logstash.drvPath;
+      {
+        elk = nixosTests.elk.ELK-7;
+      }
+    );
+};
+in this