diff --git a/core/core-popups.el b/core/core-popups.el
index 9a6f1cdfe..4b8bd7d90 100644
--- a/core/core-popups.el
+++ b/core/core-popups.el
@@ -558,6 +558,18 @@ you came from."
   (advice-add #'xref-goto-xref :around #'doom*xref-follow-and-close))
 
 
+;;
+;; Major modes
+;;
+
+(after! plantuml-mode
+  (defun doom*plantuml-preview-in-popup-window (orig-fn &rest args)
+    (save-window-excursion
+      (apply orig-fn args))
+    (pop-to-buffer plantuml-preview-buffer))
+  (advice-add #'plantuml-preview-string
+              :around #'doom*plantuml-preview-in-popup-window))
+
 ;; Ensure these settings are attached to org-load-hook as late as possible,
 ;; giving other modules a chance to add their own hooks.
 (defun doom|init-org-popups ()
diff --git a/init.example.el b/init.example.el
index 0b541be4c..1b706ab73 100644
--- a/init.example.el
+++ b/init.example.el
@@ -93,6 +93,7 @@
        ocaml           ; an objective camel
        perl            ; write code no one else can comprehend
        php             ; make php less awful to work with
+       plantuml        ; diagrams for confusing people more
        purescript      ; javascript, but functional
        python          ; beautiful is better than ugly
        rest            ; Emacs as a REST client
diff --git a/modules/lang/plantuml/autoload.el b/modules/lang/plantuml/autoload.el
new file mode 100644
index 000000000..1fbd15a96
--- /dev/null
+++ b/modules/lang/plantuml/autoload.el
@@ -0,0 +1,10 @@
+;;; lang/plantuml/autoload.el -*- lexical-binding: t; -*-
+
+;;;###autoload
+(defun +plantuml/install ()
+  "Install plantuml.jar."
+  (interactive)
+  (unless (file-exists-p plantuml-jar-path)
+    (user-error "plantuml.jar already installed"))
+  (url-copy-file "https://kent.dl.sourceforge.net/project/plantuml/plantuml.jar"
+                 plantuml-jar-path))
diff --git a/modules/lang/plantuml/config.el b/modules/lang/plantuml/config.el
new file mode 100644
index 000000000..13353d1ab
--- /dev/null
+++ b/modules/lang/plantuml/config.el
@@ -0,0 +1,18 @@
+;;; lang/plantuml/config.el -*- lexical-binding: t; -*-
+
+(def-package! plantuml-mode
+  :mode "\\.p\\(lant\\)?uml$"
+  :config
+  (setq plantuml-jar-path (concat doom-etc-dir "plantuml.jar"))
+  (set! :popup "*PLANTUML Preview*" :size 25 :noselect t :autokill t)
+
+  (unless (executable-find "java")
+    (warn "plantuml-mode: can't find java, preview disabled."))
+  (unless (file-exists-p plantuml-jar-path)
+    (warn "plantuml-mode: can't find plantuml.jar; run M-x +plantuml/install.")))
+
+
+(def-package! flycheck-plantuml
+  :when (featurep! :feature syntax-checker)
+  :after plantuml-mode
+  :config (flycheck-plantuml-setup))
diff --git a/modules/lang/plantuml/packages.el b/modules/lang/plantuml/packages.el
new file mode 100644
index 000000000..f83696e6c
--- /dev/null
+++ b/modules/lang/plantuml/packages.el
@@ -0,0 +1,6 @@
+;; -*- no-byte-compile: t; -*-
+;;; lang/plantuml/packages.el
+
+(package! plantuml-mode)
+(when (featurep! :feature syntax-checker)
+  (package! flycheck-plantuml))