diff --git a/src/honey/sql.cljc b/src/honey/sql.cljc
index afc8389..bd8cf9c 100644
--- a/src/honey/sql.cljc
+++ b/src/honey/sql.cljc
@@ -209,6 +209,9 @@
                       {:symbol x
                        :failure (str t)})))))
 
+(defn- ensure-sequential [xs]
+  (if (sequential? xs) xs [xs]))
+
 (defn format-entity
   "Given a simple SQL entity (a keyword or symbol -- or string),
   return the equivalent SQL fragment (as a string -- no parameters).
@@ -549,7 +552,7 @@
     (-> [sql'] (into params) (into params'))))
 
 (defn- format-select-into [k xs]
-  (let [[v e] (if (sequential? xs) xs [xs])
+  (let [[v e] (ensure-sequential xs)
         [sql & params] (when e (format-expr e))]
     (into [(str (sql-kw k) " " (format-entity v)
                 (when sql
@@ -708,11 +711,12 @@
     []))
 
 (defn- format-group-by [k xs]
-  (let [[sqls params] (format-expr-list xs)]
+  (let [[sqls params] (format-expr-list (ensure-sequential xs))]
     (into [(str (sql-kw k) " " (str/join ", " sqls))] params)))
 
 (defn- format-order-by [k xs]
-  (let [dirs (map #(when (sequential? %) (second %)) xs)
+  (let [xs (ensure-sequential xs)
+        dirs (map #(when (sequential? %) (second %)) xs)
         [sqls params]
         (format-expr-list (map #(if (sequential? %) (first %) %) xs))]
     (into [(str (sql-kw k) " "
@@ -722,7 +726,7 @@
                                     dirs)))] params)))
 
 (defn- format-lock-strength [k xs]
-  (let [[strength tables nowait] (if (sequential? xs) xs [xs])]
+  (let [[strength tables nowait] (ensure-sequential xs)]
     [(str (sql-kw k) " " (sql-kw strength)
           (when tables
             (str
@@ -946,7 +950,7 @@
             (format-ddl-options opts context)))))
 
 (defn- format-truncate [k xs]
-  (let [[table & options] (if (sequential? xs) xs [xs])
+  (let [[table & options] (ensure-sequential xs)
         [pre table ine options] (destructure-ddl-item [table options] "truncate")]
     (when (seq pre) (throw (ex-info "TRUNCATE syntax error" {:unexpected pre})))
     (when (seq ine) (throw (ex-info "TRUNCATE syntax error" {:unexpected ine})))
diff --git a/src/honey/sql/helpers.cljc b/src/honey/sql/helpers.cljc
index d25bd19..9a2b8b1 100644
--- a/src/honey/sql/helpers.cljc
+++ b/src/honey/sql/helpers.cljc
@@ -51,7 +51,11 @@
 ;; implementation helpers:
 
 (defn- default-merge [current args]
-  (c/into (vec current) args))
+  (let [current (cond
+                  (nil? current) []
+                  (sequential? current) (vec current)
+                  :else [current])]
+    (c/into current args)))
 
 (defn- sym->kw
   "Given a symbol, produce a keyword, retaining the namespace
diff --git a/test/honey/sql/helpers_test.cljc b/test/honey/sql/helpers_test.cljc
index be159ba..b1b4a75 100644
--- a/test/honey/sql/helpers_test.cljc
+++ b/test/honey/sql/helpers_test.cljc
@@ -144,14 +144,14 @@
 (deftest select-top-tests
   (testing "Basic TOP syntax"
     (is (= ["SELECT TOP(?) foo FROM bar ORDER BY quux ASC" 10]
-           (sql/format {:select-top [10 :foo] :from :bar :order-by [:quux]})))
+           (sql/format {:select-top [10 :foo] :from :bar :order-by :quux})))
     (is (= ["SELECT TOP(?) foo FROM bar ORDER BY quux ASC" 10]
            (sql/format (-> (select-top 10 :foo)
                            (from :bar)
                            (order-by :quux))))))
   (testing "Expanded TOP syntax"
     (is (= ["SELECT TOP(?) PERCENT WITH TIES foo, baz FROM bar ORDER BY quux ASC" 10]
-           (sql/format {:select-top [[10 :percent :with-ties] :foo :baz] :from :bar :order-by [:quux]})))
+           (sql/format {:select-top [[10 :percent :with-ties] :foo :baz] :from :bar :order-by :quux})))
     (is (= ["SELECT TOP(?) PERCENT WITH TIES foo, baz FROM bar ORDER BY quux ASC" 10]
            (sql/format (-> (select-top [10 :percent :with-ties] :foo :baz)
                            (from :bar)
@@ -865,7 +865,7 @@
                                  [[:filter ; two pairs -- alias is on last pair
                                    [:avg :x [:order-by :y [:a :desc]]] {:where [:< :i 10]}
                                    [:sum :q] {:where [:= :x nil]}] :b]
-                                 [[:within-group [:foo :y] {:order-by [:x]}]]]})
+                                 [[:within-group [:foo :y] {:order-by :x}]]]})
            [(str "SELECT COUNT(*) FILTER (WHERE i > ?) AS a,"
                  " AVG(x, y ORDER BY a DESC) FILTER (WHERE i < ?),"
                  " SUM(q) FILTER (WHERE x IS NULL) AS b,"
diff --git a/test/honey/sql/postgres_test.cljc b/test/honey/sql/postgres_test.cljc
index 03af583..9aad005 100644
--- a/test/honey/sql/postgres_test.cljc
+++ b/test/honey/sql/postgres_test.cljc
@@ -255,6 +255,12 @@
              (sql/format)))))
 
 (deftest over-test
+  (testing "simple window statement"
+    (is (= ["SELECT AVG(salary) OVER w FROM employee WINDOW w AS (PARTITION BY department ORDER BY salary ASC)"]
+           (sql/format {:select [[[:over [[:avg :salary] :w]]]]
+                        :from   :employee
+                        :window [:w {:partition-by :department
+                                     :order-by     :salary}]}))))
   (testing "window function over on select statemt"
     (is (= ["SELECT id, AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) AS Average, MAX(salary) OVER w AS MaxSalary FROM employee WINDOW w AS (PARTITION BY department)"]
            ;; honeysql treats over as a function:
diff --git a/test/honey/sql_test.cljc b/test/honey/sql_test.cljc
index 14b21fb..0c69d79 100644
--- a/test/honey/sql_test.cljc
+++ b/test/honey/sql_test.cljc
@@ -83,10 +83,14 @@
          (sut/format {:select [:*] :from [:table] :where (sut/map= {:id 1})} {:quoted true})))
   (is (= ["SELECT \"t\".* FROM \"table\" AS \"t\" WHERE \"id\" = ?" 1]
          (sut/format {:select [:t.*] :from [[:table :t]] :where [:= :id 1]} {:quoted true})))
+  (is (= ["SELECT * FROM \"table\" GROUP BY \"foo\""]
+         (sut/format {:select [:*] :from [:table] :group-by :foo} {:quoted true})))
   (is (= ["SELECT * FROM \"table\" GROUP BY \"foo\", \"bar\""]
          (sut/format {:select [:*] :from [:table] :group-by [:foo :bar]} {:quoted true})))
   (is (= ["SELECT * FROM \"table\" GROUP BY DATE(\"bar\")"]
          (sut/format {:select [:*] :from [:table] :group-by [[:date :bar]]} {:quoted true})))
+  (is (= ["SELECT * FROM \"table\" ORDER BY \"foo\" ASC"]
+         (sut/format {:select [:*] :from [:table] :order-by :foo} {:quoted true})))
   (is (= ["SELECT * FROM \"table\" ORDER BY \"foo\" DESC, \"bar\" ASC"]
          (sut/format {:select [:*] :from [:table] :order-by [[:foo :desc] :bar]} {:quoted true})))
   (is (= ["SELECT * FROM \"table\" ORDER BY DATE(\"expiry\") DESC, \"bar\" ASC"]