diff --git a/src/sort.js b/src/sort.js
index a96a14b9..8d7a41a3 100644
--- a/src/sort.js
+++ b/src/sort.js
@@ -4,7 +4,7 @@ export default function sort(values, ...F) {
   if (typeof values[Symbol.iterator] !== "function") throw new TypeError("values is not iterable");
   values = Array.from(values);
   let [f] = F;
-  if ((F.length === 1 && f.length === 1) || F.length > 1) {
+  if ((f && f.length === 1) || F.length > 1) {
     const index = Uint32Array.from(values, (d, i) => i);
     if (F.length > 1) {
       F = F.map(f => values.map(f));
diff --git a/test/sort-test.js b/test/sort-test.js
index efa02859..d551fb8c 100644
--- a/test/sort-test.js
+++ b/test/sort-test.js
@@ -61,11 +61,12 @@ it("sort(values) accepts an iterable", () => {
 });
 
 it("sort(values) enforces that values is iterable", () => {
-  assert.throws(() => sort({}), TypeError);
+  assert.throws(() => sort({}), {name: "TypeError", message: "values is not iterable"});
 });
 
 it("sort(values, comparator) enforces that comparator is a function", () => {
-  assert.throws(() => sort([], {}), TypeError);
+  assert.throws(() => sort([], {}), {name: "TypeError", message: "compare is not a function"});
+  assert.throws(() => sort([], null), {name: "TypeError", message: "compare is not a function"});
 });
 
 it("sort(values) does not skip sparse elements", () => {