diff --git a/CHANGELOG.md b/CHANGELOG.md
index 556748acc..f78020346 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@
 
 * [#546](https://github.com/clojure-emacs/cider-nrepl/pull/546): Added support for matcher-combinators to the test middleware.
 
+### Changes
+
+* [#550](https://github.com/clojure-emacs/cider-nrepl/pull/550): Always return test documentation messages as strings.
+
 ## 0.18.0 (2018-08-06)
 
 ### New features
diff --git a/src/cider/nrepl/middleware/test.clj b/src/cider/nrepl/middleware/test.clj
index 27e423048..39c7af79d 100644
--- a/src/cider/nrepl/middleware/test.clj
+++ b/src/cider/nrepl/middleware/test.clj
@@ -9,7 +9,8 @@
             [orchard.namespace :as ns]
             [orchard.query :as query]
             [clojure.pprint :as pp]
-            [clojure.test :as test]))
+            [clojure.test :as test]
+            [clojure.walk :as walk]))
 
 (if (find-ns 'clojure.tools.nrepl)
   (require
@@ -291,11 +292,18 @@
   (with-interruptible-eval
     msg
     (try
-      (let [report (test-var-query
-                    (-> var-query
-                        (assoc-in [:ns-query :has-tests?] true)
-                        (assoc :test? true)
-                        (util.coerce/var-query)))]
+      (let [stringify-msg (fn [report]
+                            (walk/postwalk (fn [x] (if (and (map? x)
+                                                            (contains? x :message))
+                                                     (update x :message str)
+                                                     x))
+                                           report))
+            report (-> var-query
+                       (assoc-in [:ns-query :has-tests?] true)
+                       (assoc :test? true)
+                       (util.coerce/var-query)
+                       test-var-query
+                       stringify-msg)]
         (reset! results (:results report))
         (t/send transport (response-for msg (u/transform-value report))))
       (catch clojure.lang.ExceptionInfo e
diff --git a/test/clj/cider/nrepl/middleware/test_filter_tests.clj b/test/clj/cider/nrepl/middleware/test_filter_tests.clj
index 67edb7e18..10e5f3971 100644
--- a/test/clj/cider/nrepl/middleware/test_filter_tests.clj
+++ b/test/clj/cider/nrepl/middleware/test_filter_tests.clj
@@ -11,3 +11,6 @@
 
 (deftest yet-an-other-test
   (is true "yet an other"))
+
+(deftest test-with-map-as-message
+  (is true {:key "val"}))
diff --git a/test/clj/cider/nrepl/middleware/test_test.clj b/test/clj/cider/nrepl/middleware/test_test.clj
index 6dcb5aea0..9b0086780 100644
--- a/test/clj/cider/nrepl/middleware/test_test.clj
+++ b/test/clj/cider/nrepl/middleware/test_test.clj
@@ -52,8 +52,8 @@
                                                               :exclude       ["integration"]})
           tests (keys (:cider.nrepl.middleware.test-filter-tests results))]
       (is ((set (keys results)) :cider.nrepl.middleware.test-filter-tests) "ns that contains smoke is present")
-      (is (= 2 (count tests)) "only one test was run")
-      (is (= #{:a-puff-of-smoke-test :yet-an-other-test} (set tests)) "only the test marked 'smoke' was run")))
+      (is (= 3 (count tests)) "only one test was run")
+      (is (= #{:a-puff-of-smoke-test :yet-an-other-test :test-with-map-as-message} (set tests)) "only the test marked 'smoke' was run")))
   (testing "marked test is still run if filter is not used"
     (let [{:keys [results] :as test-result} (session/message {:op            "test"
                                                               :ns            "cider.nrepl.middleware.test-filter-tests"})
@@ -86,8 +86,8 @@
                                                                           :exclude-meta-key ["integration"]}})
           tests (keys (:cider.nrepl.middleware.test-filter-tests results))]
       (is ((set (keys results)) :cider.nrepl.middleware.test-filter-tests) "ns that contains smoke is present")
-      (is (= 2 (count tests)) "only one test was run")
-      (is (= #{:a-puff-of-smoke-test :yet-an-other-test} (set tests)) "only the test marked 'smoke' was run")))
+      (is (= 3 (count tests)) "only one test was run")
+      (is (= #{:a-puff-of-smoke-test :yet-an-other-test :test-with-map-as-message} (set tests)) "only the test marked 'smoke' was run")))
   (testing "marked test is still run if filter is not used"
     (let [{:keys [results] :as test-result} (session/message {:op "test-var-query"
                                                               :var-query {:ns-query {:exactly ["cider.nrepl.middleware.test-filter-tests"]}}})
@@ -95,3 +95,14 @@
       (is ((set (keys results)) :cider.nrepl.middleware.test-filter-tests) "ns that contains smoke is present")
       (is (< 1 (count tests)) "more tests were run")
       (is ((set tests) :a-puff-of-smoke-test) "smoke test is still present without a filter"))))
+
+(deftest run-test-with-map-as-documentation-message
+  (testing "documentation message map is returned as string"
+    (let [{:keys [results] :as test-result} (session/message {:op "test"
+                                                              :ns "cider.nrepl.middleware.test-filter-tests"
+                                                              :tests ["test-with-map-as-message"]})]
+      (is (= (str {:key "val"}) (-> results
+                                    :cider.nrepl.middleware.test-filter-tests
+                                    :test-with-map-as-message
+                                    first
+                                    :message))))))