diff --git a/src/ziggurat/metrics.clj b/src/ziggurat/metrics.clj
index a1a659c4..fcf6279e 100644
--- a/src/ziggurat/metrics.clj
+++ b/src/ziggurat/metrics.clj
@@ -10,10 +10,10 @@
 (defonce metrics-registry
   (MetricRegistry.))
 
-(defn- merge-tags
+(defn merge-tags
   [additional-tags]
   (let [default-tags {"actor" (:app-name (ziggurat-config))}]
-    (merge default-tags (when-not (seq additional-tags)
+    (merge default-tags (when-not (empty? additional-tags)
                           (stringify-keys additional-tags)))))
 
 (defn mk-meter
diff --git a/test/ziggurat/metrics_test.clj b/test/ziggurat/metrics_test.clj
index 8ae9c3ac..3509d8a4 100644
--- a/test/ziggurat/metrics_test.clj
+++ b/test/ziggurat/metrics_test.clj
@@ -1,8 +1,29 @@
 (ns ziggurat.metrics-test
   (:require [clojure.test :refer :all]
+            [ziggurat.config :refer [ziggurat-config]]
+            [ziggurat.fixtures :as fix]
             [ziggurat.metrics :as metrics])
   (:import (io.dropwizard.metrics5 Meter Histogram UniformReservoir)))
 
+(use-fixtures :once fix/mount-only-config-and-producer)
+
+(deftest merge-tags-test
+  (let [service-name (:app-name (ziggurat-config))]
+    (testing "additional-tags is an empty map"
+      (is (= (metrics/merge-tags {}) {"actor" service-name})))
+    (testing "additional-tags is not empty"
+      (is (= (metrics/merge-tags {:foo "bar"}) {"actor" service-name "foo" "bar"})))
+    (testing "additional-tags is nil"
+      (is (= (metrics/merge-tags nil) {"actor" service-name})))))
+
+(deftest intercalate-dot-test
+  (testing "empty vector"
+    (is (= (metrics/intercalate-dot []) "")))
+  (testing "non-empty vector"
+    (is (= (metrics/intercalate-dot ["test" "mic" "123"]) "test.mic.123")))
+  (testing "nil"
+    (is (= (metrics/intercalate-dot nil) ""))))
+
 (deftest mk-meter-test
   (testing "returns a meter"
     (let [category "category"