diff --git a/plantuml-mode.el b/plantuml-mode.el
index c411308..94d1644 100644
--- a/plantuml-mode.el
+++ b/plantuml-mode.el
@@ -586,7 +586,7 @@ or it is followed by line end.")
       (defvar plantuml-indent-regexp-footer-start "^\s*\\(?:\\(?:center\\|left\\|right\\)\s+footer\\|footer\\)\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-legend-start "^\s*\\(?:legend\\|legend\s+\\(?:bottom\\|top\\)\\|legend\s+\\(?:center\\|left\\|right\\)\\|legend\s+\\(?:bottom\\|top\\)\s+\\(?:center\\|left\\|right\\)\\)\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-oldif-start "^.*if\s+\".*\"\s+then\s*\\('.*\\)?$" "used in current activity diagram, sometimes already mentioned as deprecated")
-      (defvar plantuml-indent-regexp-newif-start "^\s*if\s+(.*)\s+then\s*.*$")
+      (defvar plantuml-indent-regexp-newif-start "^\s*\\(?:else\\)?if\s+(.*)\s+then\s*.*$")
       (defvar plantuml-indent-regexp-macro-start "^\s*!definelong.*$")
       (defvar plantuml-indent-regexp-user-control-start "^.*'.*\s*PLANTUML_MODE_INDENT_INCREASE\s*.*$")
       (defvar plantuml-indent-regexp-start (list plantuml-indent-regexp-block-start
@@ -614,7 +614,7 @@ or it is followed by line end.")
       (defvar plantuml-indent-regexp-footer-end "^\s*endfooter\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-legend-end "^\s*endlegend\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-oldif-end "^\s*\\(endif\\|else\\)\s*\\('.*\\)?$")
-      (defvar plantuml-indent-regexp-newif-end "^\s*\\(endif\\|else\\)\s*.*$")
+      (defvar plantuml-indent-regexp-newif-end "^\s*\\(endif\\|elseif\\|else\\)\s*.*$")
       (defvar plantuml-indent-regexp-macro-end "^\s*!enddefinelong\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-user-control-end "^.*'.*\s*PLANTUML_MODE_INDENT_DECREASE\s*.*$")
       (defvar plantuml-indent-regexp-end (list plantuml-indent-regexp-block-end
diff --git a/test/plantuml-indentation-activity-new-test.el b/test/plantuml-indentation-activity-new-test.el
new file mode 100644
index 0000000..b097df5
--- /dev/null
+++ b/test/plantuml-indentation-activity-new-test.el
@@ -0,0 +1,75 @@
+;;; plantuml-indentation-activity-old-test.el --- PlantUML Mode indentation tests   -*- lexical-binding: t; -*-
+
+;; Author: René Schmelzer
+;; Maintainer: Carlo Sciolla (skuro)
+;; URL: https://github.com/skuro/plantuml-mode
+
+;;; Commentary:
+
+;; Test indentation for activity (old version) diagrams.
+
+;;; Code:
+
+
+(ert-deftest plantuml-test-indentation/activity-new/start-stop ()
+  "Test correct indentation of plantuml activity-new diagram elements: start-stop.
+These code examples are taken from www.plantuml.com"
+  (plantuml-test-indent-block
+"@startuml
+start
+:Hello world;
+:This is defined on
+several **lines**;
+end
+@enduml"
+
+"@startuml
+start
+:Hello world;
+:This is defined on
+several **lines**;
+end
+@enduml"))
+
+(ert-deftest plantuml-test-indentation/activity-new/conditional ()
+  "Test correct indentation of plantuml activity-new diagram conditionals.
+These code examples are taken from www.plantuml.com"
+  (plantuml-test-indent-block
+"@startuml
+start
+if (condition A) then (yes)
+:Text 1;
+elseif (condition B) then (yes)
+:Text 2;
+stop
+elseif (condition C) then (yes)
+:Text 3;
+elseif (condition D) then (yes)
+:Text 4;
+else (nothing)
+:Text else;
+endif
+stop
+@enduml"
+
+"@startuml
+start
+if (condition A) then (yes)
+  :Text 1;
+elseif (condition B) then (yes)
+  :Text 2;
+  stop
+elseif (condition C) then (yes)
+  :Text 3;
+elseif (condition D) then (yes)
+  :Text 4;
+else (nothing)
+  :Text else;
+endif
+stop
+@enduml"))
+
+
+(provide 'plantuml-indentation-activity-new-test)
+
+;;; plantuml-indentation-activity-old-test.el ends here