diff --git a/emacs/notmuch-draft.el b/emacs/notmuch-draft.el
index 2939da55..a68b7d8d 100644
--- a/emacs/notmuch-draft.el
+++ b/emacs/notmuch-draft.el
@@ -27,6 +27,7 @@
 
 (require 'cl-lib)
 (require 'pcase)
+(require 'subr-x)
 
 (require 'notmuch-maildir-fcc)
 (require 'notmuch-tag)
diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index 6130309a..05d3be10 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -23,6 +23,7 @@
 
 (require 'cl-lib)
 (require 'pcase)
+(require 'subr-x)
 
 (require 'mm-util)
 (require 'mm-view)
diff --git a/emacs/notmuch-message.el b/emacs/notmuch-message.el
index b90c934a..0856a2e9 100644
--- a/emacs/notmuch-message.el
+++ b/emacs/notmuch-message.el
@@ -23,6 +23,7 @@
 
 (require 'cl-lib)
 (require 'pcase)
+(require 'subr-x)
 
 (require 'message)
 (require 'notmuch-tag)
diff --git a/emacs/notmuch-parser.el b/emacs/notmuch-parser.el
index 9749a6be..f04b07c2 100644
--- a/emacs/notmuch-parser.el
+++ b/emacs/notmuch-parser.el
@@ -23,6 +23,7 @@
 
 (require 'cl-lib)
 (require 'pcase)
+(require 'subr-x)
 
 (defun notmuch-sexp-create-parser ()
   "Return a new streaming S-expression parser.