diff --git a/emacs/notmuch.el b/emacs/notmuch.el
index b8d9c444..5a8c9570 100644
--- a/emacs/notmuch.el
+++ b/emacs/notmuch.el
@@ -58,6 +58,7 @@
 (require 'notmuch-hello)
 (require 'notmuch-maildir-fcc)
 (require 'notmuch-message)
+(require 'notmuch-parser)
 
 (defcustom notmuch-search-result-format
   `(("date" . "%12s ")
@@ -809,13 +810,6 @@ non-authors is found, assume that all of the authors match."
 	(setq notmuch-search-target-thread "found")
 	(goto-char beg)))))
 
-(defun notmuch-search-show-error (string &rest objects)
-  (save-excursion
-    (goto-char (point-max))
-    (insert "Error: Unexpected output from notmuch search:\n")
-    (insert (apply #'format string objects))
-    (insert "\n")))
-
 (defun notmuch-search-process-filter (proc string)
   "Process and filter the output of \"notmuch search\""
   (let ((results-buf (process-buffer proc))
@@ -829,8 +823,7 @@ non-authors is found, assume that all of the authors match."
 	(save-excursion
 	  (goto-char (point-max))
 	  (insert string))
-	(notmuch-json-parse-partial-list 'notmuch-search-show-result
-					 'notmuch-search-show-error
+	(notmuch-sexp-parse-partial-list 'notmuch-search-show-result
 					 results-buf)))))
 
 (defun notmuch-search-tag-all (&optional tag-changes)
@@ -933,7 +926,7 @@ Other optional parameters are used as follows:
       (save-excursion
 	(let ((proc (notmuch-start-notmuch
 		     "notmuch-search" buffer #'notmuch-search-process-sentinel
-		     "search" "--format=json" "--format-version=1"
+		     "search" "--format=sexp" "--format-version=1"
 		     (if oldest-first
 			 "--sort=oldest-first"
 		       "--sort=newest-first")
diff --git a/test/emacs b/test/emacs
index e3cf4690..5bc3efcc 100755
--- a/test/emacs
+++ b/test/emacs
@@ -858,7 +858,7 @@ test_expect_success "Rendering HTML mail with images" \
 test_begin_subtest "Search handles subprocess error exit codes"
 cat > notmuch_fail <<EOF
 #!/bin/sh
-echo This is output
+echo '()'
 exit 1
 EOF
 chmod a+x notmuch_fail
@@ -873,21 +873,19 @@ test_emacs "(let ((notmuch-command \"$PWD/notmuch_fail\"))
 	       (test-output))"
 sed -i -e 's/^\[.*\]$/[XXX]/' ERROR
 test_expect_equal "$(cat OUTPUT; echo ---; cat MESSAGES; echo ---; cat ERROR)" "\
-Error: Unexpected output from notmuch search:
-This is output
 End of search results.
 ---
 $PWD/notmuch_fail exited with status 1 (see *Notmuch errors* for more details)
 ---
 [XXX]
 $PWD/notmuch_fail exited with status 1
-command: $PWD/notmuch_fail search --format\=json --format-version\=1 --sort\=newest-first tag\:inbox
+command: $PWD/notmuch_fail search --format\=sexp --format-version\=1 --sort\=newest-first tag\:inbox
 exit status: 1"
 
 test_begin_subtest "Search handles subprocess warnings"
 cat > notmuch_fail <<EOF
 #!/bin/sh
-echo This is output
+echo '()'
 echo This is a warning >&2
 echo This is another warning >&2
 exit 0
@@ -905,8 +903,6 @@ test_emacs "(let ((notmuch-command \"$PWD/notmuch_fail\"))
 	       (test-output))"
 sed -i -e 's/^\[.*\]$/[XXX]/' ERROR
 test_expect_equal "$(cat OUTPUT; echo ---; cat MESSAGES; echo ---; cat ERROR)" "\
-Error: Unexpected output from notmuch search:
-This is output
 End of search results.
 ---
 This is a warning (see *Notmuch errors* for more details)