diff --git a/plantuml-mode.el b/plantuml-mode.el
index e40ba0d..823e05e 100644
--- a/plantuml-mode.el
+++ b/plantuml-mode.el
@@ -578,7 +578,7 @@ might follow).")
         "Indentation regex for plantuml group elements that are defined for sequence diagrams.
 Two variants for groups: keyword is either followed by whitespace and some text
 or it is followed by line end.")
-      (defvar plantuml-indent-regexp-activate-start "^\s*activate\s+.+$")
+      (defvar plantuml-indent-regexp-activate-start "^\s*\\(activate\s+.+\\|[^\\+]+\\+\\+.*\\)$")
       (defvar plantuml-indent-regexp-box-start "^\s*box\s+.+$")
       (defvar plantuml-indent-regexp-ref-start "^\s*ref\s+over\s+[^:]+?$")
       (defvar plantuml-indent-regexp-title-start "^\s*title\s*\\('.*\\)?$")
@@ -610,7 +610,7 @@ or it is followed by line end.")
       (defvar plantuml-indent-regexp-block-end "^\s*\\(?:}\\|endif\\|else\s*.*\\|end\\)\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-note-end "^\s*\\(end\s+note\\|end[rh]note\\)\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-group-end "^\s*end\s*\\('.*\\)?$")
-      (defvar plantuml-indent-regexp-activate-end "^\s*deactivate\s+.+$")
+      (defvar plantuml-indent-regexp-activate-end "^\s*\\(deactivate\s+.+\\|return\\(\s+.+\\)?\\)$")
       (defvar plantuml-indent-regexp-box-end "^\s*end\s+box\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-ref-end "^\s*end\s+ref\s*\\('.*\\)?$")
       (defvar plantuml-indent-regexp-title-end "^\s*end\s+title\s*\\('.*\\)?$")