diff --git a/.travis.yml b/.travis.yml
index d9e866d..62d76e3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,8 @@
 language: clojure
 sudo: required
 lein: lein
+dist: xenial
 before_script:
-  - ./bin/ci/install_mongodb.sh
   - mongod --version
   - ./bin/ci/before_script.sh
 script: lein do clean, javac, test
diff --git a/bin/ci/before_script.sh b/bin/ci/before_script.sh
index 711d6dd..77f1a97 100755
--- a/bin/ci/before_script.sh
+++ b/bin/ci/before_script.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 # MongoDB seems to need some time to boot first. MK.
-sleep 5
+sleep 15
 
 # MongoDB Java driver won't run authentication twice on the same DB instance,
 # so we need to use multiple DBs.
diff --git a/src/clojure/monger/core.clj b/src/clojure/monger/core.clj
index 880a259..e5314a0 100644
--- a/src/clojure/monger/core.clj
+++ b/src/clojure/monger/core.clj
@@ -233,10 +233,11 @@
    Commonly used for PaaS-based applications, for example, running on Heroku.
    If username and password are provided, performs authentication."
   [^String uri-string]
-  (let [uri  (MongoClientURI. uri-string)
-        conn (MongoClient. uri)
-        db   (.getDB conn (.getDatabase uri))]
-    {:conn conn :db db}))
+  (let [uri    (MongoClientURI. uri-string)
+        conn   (MongoClient. uri)]
+    (if-let [dbName (.getDatabase uri)]
+      {:conn conn :db (.getDB conn dbName)}
+      (throw (IllegalArgumentException. "No database name specified in URI. Monger requires a database to be explicitly configured.")))))
 
 (defn ^com.mongodb.CommandResult command
   "Runs a database command (please check MongoDB documentation for the complete list of commands).
diff --git a/test/monger/test/core_test.clj b/test/monger/test/core_test.clj
index eeaa5b6..02f45dc 100644
--- a/test/monger/test/core_test.clj
+++ b/test/monger/test/core_test.clj
@@ -70,3 +70,7 @@
               :cursor-finalizer-enabled true
               :required-replica-set-name "rs"}]
     (is (instance? com.mongodb.MongoClientOptions$Builder (mg/mongo-options-builder opts)))))
+
+(deftest connect-to-uri-without-db-name
+  (let [uri "mongodb://localhost:27017"]
+    (is (thrown? IllegalArgumentException (mg/connect-via-uri uri)))))