diff --git a/src/js/util.ts b/src/js/util.ts
index 61a28d3..976e6c4 100644
--- a/src/js/util.ts
+++ b/src/js/util.ts
@@ -92,10 +92,10 @@ export const valueToJsonString = (
  */
 export const roundToPrecision = (value: number, bit: number = 0): number => {
   if (!Number.isFinite(value)) {
-    throw new TypeError(`${value} is not a number.`);
+    throw new TypeError(`${value} is not a finite number.`);
   }
   if (!Number.isFinite(bit)) {
-    throw new TypeError(`${bit} is not a number.`);
+    throw new TypeError(`${bit} is not a finite number.`);
   } else if (bit < 0 || bit > HEX) {
     throw new RangeError(`${bit} is not between 0 and ${HEX}.`);
   }
@@ -126,10 +126,10 @@ export const interpolateHue = (
   arc: string = 'shorter'
 ): Array<number> => {
   if (!Number.isFinite(hueA)) {
-    throw new TypeError(`${hueA} is not a number.`);
+    throw new TypeError(`${hueA} is not a finite number.`);
   }
   if (!Number.isFinite(hueB)) {
-    throw new TypeError(`${hueB} is not a number.`);
+    throw new TypeError(`${hueB} is not a finite number.`);
   }
   switch (arc) {
     case 'decreasing': {
diff --git a/test/util.test.ts b/test/util.test.ts
index 9b8b4a4..31acab8 100644
--- a/test/util.test.ts
+++ b/test/util.test.ts
@@ -177,14 +177,22 @@ describe('round to specified precision', () => {
   const func = util.roundToPrecision;
 
   it('should throw', () => {
-    assert.throws(() => func(), TypeError, 'undefined is not a number.');
+    assert.throws(() => func(), TypeError, 'undefined is not a finite number.');
+  });
+
+  it('should throw', () => {
+    assert.throws(
+      () => func(Infinity),
+      TypeError,
+      'Infinity is not a finite number.'
+    );
   });
 
   it('should throw', () => {
     assert.throws(
       () => func(1.23456789, 'foo'),
       TypeError,
-      'foo is not a number.'
+      'foo is not a finite number.'
     );
   });
 
@@ -269,11 +277,15 @@ describe('interpolate hue', () => {
   const func = util.interpolateHue;
 
   it('should throw', () => {
-    assert.throws(() => func(), TypeError, 'undefined is not a number.');
+    assert.throws(() => func(), TypeError, 'undefined is not a finite number.');
   });
 
   it('should throw', () => {
-    assert.throws(() => func(90), TypeError, 'undefined is not a number.');
+    assert.throws(
+      () => func(90),
+      TypeError,
+      'undefined is not a finite number.'
+    );
   });
 
   it('should get value', () => {