diff --git a/src/legends.js b/src/legends.js
index 64215ebaf3..612795c977 100644
--- a/src/legends.js
+++ b/src/legends.js
@@ -50,6 +50,7 @@ function legendColor(color, {legend = true, ...options}) {
     case "swatches":
       return legendSwatches(color, options);
     case "ramp":
+      if (color.domain.length < 2) return;
       return legendRamp(color, options);
     default:
       throw new Error(`unknown legend type: ${legend}`);
diff --git a/test/legend-test.js b/test/legend-test.js
index f66aa45c2a..7e03740e97 100644
--- a/test/legend-test.js
+++ b/test/legend-test.js
@@ -6,6 +6,11 @@ it(`Plot.legend({color: {type: "identity"}}) returns undefined`, () => {
   assert.strictEqual(Plot.legend({color: {type: "identity"}}), undefined);
 });
 
+it(`Plot.legend({color: {domain: [x?]}}) returns undefined`, () => {
+  assert.strictEqual(Plot.legend({color: {domain: []}}), undefined);
+  assert.strictEqual(Plot.legend({color: {domain: [1]}}), undefined);
+});
+
 it(`Plot.legend({legend: "swatches", color: {type: "<not-ordinal>"}}) throws an error`, () => {
   assert.throws(() => Plot.legend({legend: "swatches", color: {type: "linear"}}), /swatches legend requires ordinal/);
   assert.throws(() => Plot.legend({legend: "swatches", color: {type: "linear"}}), /\(not linear\)/);