diff --git a/helm-org-ql.el b/helm-org-ql.el
index b954b09..059a965 100644
--- a/helm-org-ql.el
+++ b/helm-org-ql.el
@@ -28,83 +28,85 @@
 
 ;;; Code:
 
-;;;; Requirements
+(eval-and-compile
 
-(require 'org)
+  (eval-when-compile
+    ;; Require these when compiling, but not necessarily on load.
+    (require 'org)
 
-(require 'org-ql)
-(require 'org-ql-search)
-
-;; (require 'helm)
-;; (require 'helm-org)
+    (require 'org-ql)
+    (require 'org-ql-search))
 
 ;;;; Compatibility
 
-;; Declare Helm functions since Helm may not be installed.
-(declare-function helm "ext:helm")
-(declare-function helm-run-after-exit "ext:helm")
-(declare-function helm-window "ext:helm-lib")
-(declare-function helm-buffer-get "ext:helm-lib")
-(declare-function helm-make-source "ext:helm-source")
-(declare-function helm-org-goto-marker "ext:helm-org")
+  ;; Declare Helm functions since Helm may not be installed.
+  (declare-function helm "ext:helm")
+  (declare-function helm-run-after-exit "ext:helm")
+  (declare-function helm-window "ext:helm-lib")
+  (declare-function helm-buffer-get "ext:helm-lib")
+  (declare-function helm-make-source "ext:helm-source")
+  (declare-function helm-org-goto-marker "ext:helm-org")
 
-;; Silence byte-compiler about variables.
-(defvar helm-map)
-(defvar helm-pattern)
-(defvar helm-input-idle-delay)
+  ;; Silence byte-compiler about variables.
+  (defvar helm-map)
+  (defvar helm-pattern)
+  (defvar helm-input-idle-delay)
+
+  (when (require 'helm nil 'noerror)
+
+    ;; Requirements.
+    (require 'helm-org)
 
 ;;;; Variables
 
-(defvar helm-org-ql-map
-  (let ((map (make-sparse-keymap))
-        (mappings '(
-                    "C-x C-s" helm-org-ql-save
-                    )))
-    (cl-loop for (key fn) on mappings by #'cddr
-             do (define-key map (kbd key) fn))
-    (make-composed-keymap map helm-map))
-  "Keymap for `helm-org-ql' sessions.
+    (defvar helm-org-ql-map
+      (let ((map (make-sparse-keymap))
+            (mappings '("C-x C-s" helm-org-ql-save)))
+        (cl-loop for (key fn) on mappings by #'cddr
+                 do (define-key map (kbd key) fn))
+        (make-composed-keymap map helm-map))
+      "Keymap for `helm-org-ql' sessions.
 Based on `helm-map'.")
 
-(defvar helm-source-org-ql-views
-  (helm-make-source "Org QL Views" 'helm-source-sync
-    :candidates (lambda ()
-                  (->> org-ql-views
-                       (-map #'car)
-                       (-sort #'string<)))
-    :action (list (cons "Show view" #'org-ql-view)))
-  "Helm source for `org-ql-views'.")
+    (defvar helm-source-org-ql-views
+      (helm-make-source "Org QL Views" 'helm-source-sync
+        :candidates (lambda ()
+                      (->> org-ql-views
+                           (-map #'car)
+                           (-sort #'string<)))
+        :action (list (cons "Show view" #'org-ql-view)))
+      "Helm source for `org-ql-views'.")
 
-(defvar-local helm-org-ql-buffers-files nil
-  "Used for `helm-org-ql-save'.")
+    (defvar-local helm-org-ql-buffers-files nil
+      "Used for `helm-org-ql-save'.")
 
 ;;;; Customization
 
-(defgroup helm-org-ql nil
-  "Options for `helm-org-ql'."
-  :group 'org-ql)
+    (defgroup helm-org-ql nil
+      "Options for `helm-org-ql'."
+      :group 'org-ql)
 
-(defcustom helm-org-ql-reverse-paths t
-  "Whether to reverse Org outline paths in `helm-org-ql' results."
-  :type 'boolean)
+    (defcustom helm-org-ql-reverse-paths t
+      "Whether to reverse Org outline paths in `helm-org-ql' results."
+      :type 'boolean)
 
-(defcustom helm-org-ql-input-idle-delay 0.25
-  "Seconds to wait after typing stops before running query."
-  :type 'number)
+    (defcustom helm-org-ql-input-idle-delay 0.25
+      "Seconds to wait after typing stops before running query."
+      :type 'number)
 
-(defcustom helm-org-ql-actions
-  (list (cons "Show heading in source buffer" 'helm-org-ql-show-marker)
-        (cons "Show heading in indirect buffer" 'helm-org-ql-show-marker-indirect))
-  "Alist of actions for `helm-org-ql' commands."
-  :type '(alist :key-type (string :tag "Description")
-                :value-type (function :tag "Command")))
+    (defcustom helm-org-ql-actions
+      (list (cons "Show heading in source buffer" 'helm-org-ql-show-marker)
+            (cons "Show heading in indirect buffer" 'helm-org-ql-show-marker-indirect))
+      "Alist of actions for `helm-org-ql' commands."
+      :type '(alist :key-type (string :tag "Description")
+                    :value-type (function :tag "Command")))
 
 ;;;; Commands
 
 ;;;###autoload
-(cl-defun helm-org-ql (buffers-files
-                       &key (boolean 'and) (name "helm-org-ql"))
-  "Display results in BUFFERS-FILES for an `org-ql' non-sexp query using Helm.
+    (cl-defun helm-org-ql (buffers-files
+                           &key (boolean 'and) (name "helm-org-ql"))
+      "Display results in BUFFERS-FILES for an `org-ql' non-sexp query using Helm.
 Interactively, search the current buffer.  Note that this command
 only accepts non-sexp, \"plain\" queries.
 
@@ -131,99 +133,99 @@ However, quoted strings remain quoted, so this input:
 Is transformed into this query:
 
     (and \"something else\" (tags \"funny\"))"
-  (interactive (list (current-buffer)))
-  (let ((boolean (if current-prefix-arg 'or boolean))
-        (helm-input-idle-delay helm-org-ql-input-idle-delay))
-    (helm :prompt (format "Query (boolean %s): " (-> boolean symbol-name upcase))
-          :sources (helm-org-ql-source buffers-files :name name))))
+      (interactive (list (current-buffer)))
+      (let ((boolean (if current-prefix-arg 'or boolean))
+            (helm-input-idle-delay helm-org-ql-input-idle-delay))
+        (helm :prompt (format "Query (boolean %s): " (-> boolean symbol-name upcase))
+              :sources (helm-org-ql-source buffers-files :name name))))
 
 ;;;###autoload
-(defun helm-org-ql-agenda-files ()
-  "Search agenda files with `helm-org-ql', which see."
-  (interactive)
-  (helm-org-ql (org-agenda-files) :name "Org Agenda Files"))
+    (defun helm-org-ql-agenda-files ()
+      "Search agenda files with `helm-org-ql', which see."
+      (interactive)
+      (helm-org-ql (org-agenda-files) :name "Org Agenda Files"))
 
 ;;;###autoload
-(defun helm-org-ql-org-directory ()
-  "Search Org files in `org-directory' with `helm-org-ql'."
-  (interactive)
-  (helm-org-ql (org-ql-search-directories-files)
-               :name "Org Directory Files"))
+    (defun helm-org-ql-org-directory ()
+      "Search Org files in `org-directory' with `helm-org-ql'."
+      (interactive)
+      (helm-org-ql (org-ql-search-directories-files)
+                   :name "Org Directory Files"))
 
-(defun helm-org-ql-show-marker (marker)
-  "Show heading at MARKER."
-  (interactive)
-  ;; This function is necessary because `helm-org-goto-marker' calls
-  ;; `re-search-backward' to go backward to the start of a heading,
-  ;; which, when the marker is already at the desired heading, causes
-  ;; it to go to the previous heading.  I don't know why it does that.
-  (switch-to-buffer (marker-buffer marker))
-  (goto-char marker)
-  (org-show-entry))
+    (defun helm-org-ql-show-marker (marker)
+      "Show heading at MARKER."
+      (interactive)
+      ;; This function is necessary because `helm-org-goto-marker' calls
+      ;; `re-search-backward' to go backward to the start of a heading,
+      ;; which, when the marker is already at the desired heading, causes
+      ;; it to go to the previous heading.  I don't know why it does that.
+      (switch-to-buffer (marker-buffer marker))
+      (goto-char marker)
+      (org-show-entry))
 
-(defun helm-org-ql-show-marker-indirect (marker)
-  "Show heading at MARKER with `org-tree-to-indirect-buffer'."
-  (interactive)
-  (helm-org-ql-show-marker marker)
-  (org-tree-to-indirect-buffer))
+    (defun helm-org-ql-show-marker-indirect (marker)
+      "Show heading at MARKER with `org-tree-to-indirect-buffer'."
+      (interactive)
+      (helm-org-ql-show-marker marker)
+      (org-tree-to-indirect-buffer))
 
-(defun helm-org-ql-save ()
-  "Show `helm-org-ql' search in an `org-ql-search' buffer."
-  (interactive)
-  (let ((buffers-files (with-current-buffer (helm-buffer-get)
-                         helm-org-ql-buffers-files))
-        (query (org-ql--plain-query helm-pattern)))
-    (helm-run-after-exit #'org-ql-search buffers-files query)))
+    (defun helm-org-ql-save ()
+      "Show `helm-org-ql' search in an `org-ql-search' buffer."
+      (interactive)
+      (let ((buffers-files (with-current-buffer (helm-buffer-get)
+                             helm-org-ql-buffers-files))
+            (query (org-ql--plain-query helm-pattern)))
+        (helm-run-after-exit #'org-ql-search buffers-files query)))
 
 ;;;###autoload
-(defun helm-org-ql-views ()
-  "Show an `org-ql' view selected with Helm."
-  (interactive)
-  (helm :sources helm-source-org-ql-views))
+    (defun helm-org-ql-views ()
+      "Show an `org-ql' view selected with Helm."
+      (interactive)
+      (helm :sources helm-source-org-ql-views))
 
 ;;;; Functions
 
-(cl-defun helm-org-ql-source (buffers-files &key (name "helm-org-ql"))
-  "Return Helm source named NAME that searches BUFFERS-FILES with `helm-org-ql'."
-  ;; Expansion of `helm-build-sync-source' macro.
-  (helm-make-source name 'helm-source-sync
-    :candidates (lambda ()
-                  (let* ((query (org-ql--plain-query helm-pattern))
-                         (window-width (window-width (helm-window))))
-                    (when query
-                      (with-current-buffer (helm-buffer-get)
-                        (setq helm-org-ql-buffers-files buffers-files))
-                      (ignore-errors
-                        ;; Ignore errors that might be caused by partially typed queries.
-                        (org-ql-select buffers-files query
-                          :action `(helm-org-ql--heading ,window-width))))))
-    :match #'identity
-    :fuzzy-match nil
-    :multimatch nil
-    :nohighlight t
-    :volatile t
-    :keymap helm-org-ql-map
-    :action helm-org-ql-actions))
+    (cl-defun helm-org-ql-source (buffers-files &key (name "helm-org-ql"))
+      "Return Helm source named NAME that searches BUFFERS-FILES with `helm-org-ql'."
+      ;; Expansion of `helm-build-sync-source' macro.
+      (helm-make-source name 'helm-source-sync
+        :candidates (lambda ()
+                      (let* ((query (org-ql--plain-query helm-pattern))
+                             (window-width (window-width (helm-window))))
+                        (when query
+                          (with-current-buffer (helm-buffer-get)
+                            (setq helm-org-ql-buffers-files buffers-files))
+                          (ignore-errors
+                            ;; Ignore errors that might be caused by partially typed queries.
+                            (org-ql-select buffers-files query
+                              :action `(helm-org-ql--heading ,window-width))))))
+        :match #'identity
+        :fuzzy-match nil
+        :multimatch nil
+        :nohighlight t
+        :volatile t
+        :keymap helm-org-ql-map
+        :action helm-org-ql-actions))
 
-(defun helm-org-ql--heading (window-width)
-  "Return string for Helm for heading at point.
+    (defun helm-org-ql--heading (window-width)
+      "Return string for Helm for heading at point.
 WINDOW-WIDTH should be the width of the Helm window."
-  (font-lock-ensure (point-at-bol) (point-at-eol))
-  ;; TODO: It would be better to avoid calculating the prefix and width
-  ;; at each heading, but there's no easy way to do that once in each
-  ;; buffer, unless we manually called `org-ql' in each buffer, which
-  ;; I'd prefer not to do.  Maybe I should add a feature to `org-ql' to
-  ;; call a setup function in a buffer before running queries.
-  (let* ((prefix (concat (buffer-name) ":"))
-         (width (- window-width (length prefix)))
-         (heading (org-get-heading t))
-         (path (-> (org-get-outline-path)
-                   (org-format-outline-path width nil "")
-                   (org-split-string "")))
-         (path (if helm-org-ql-reverse-paths
-                   (concat heading "\\" (s-join "\\" (nreverse path)))
-                 (concat (s-join "/" path) "/" heading))))
-    (cons (concat prefix path) (point-marker))))
+      (font-lock-ensure (point-at-bol) (point-at-eol))
+      ;; TODO: It would be better to avoid calculating the prefix and width
+      ;; at each heading, but there's no easy way to do that once in each
+      ;; buffer, unless we manually called `org-ql' in each buffer, which
+      ;; I'd prefer not to do.  Maybe I should add a feature to `org-ql' to
+      ;; call a setup function in a buffer before running queries.
+      (let* ((prefix (concat (buffer-name) ":"))
+             (width (- window-width (length prefix)))
+             (heading (org-get-heading t))
+             (path (-> (org-get-outline-path)
+                       (org-format-outline-path width nil "")
+                       (org-split-string "")))
+             (path (if helm-org-ql-reverse-paths
+                       (concat heading "\\" (s-join "\\" (nreverse path)))
+                     (concat (s-join "/" path) "/" heading))))
+        (cons (concat prefix path) (point-marker))))))
 
 ;;;; Footer