diff --git a/src/line.ts b/src/line.ts
index bca11ac..277ef12 100755
--- a/src/line.ts
+++ b/src/line.ts
@@ -144,6 +144,11 @@ export class Line implements GeoShape {
     return this.shift(p.x, p.y);
   }
 
+  /** Reverse the line's start and end points. */
+  flip() {
+    return this.make(this.p2, this.p1)
+  }
+
   equals(other: Line, tolerance?: number) {
     // Note: Checking line types breaks some applications in Mathigon textbooks.
     // if (other.type !== 'line') return false;
diff --git a/test/line-test.ts b/test/line-test.ts
index f0a865a..dd92fa0 100644
--- a/test/line-test.ts
+++ b/test/line-test.ts
@@ -42,3 +42,12 @@ tape('line intercepts', (test) => {
 
   test.end();
 });
+
+tape('flip', (test) => {
+  const a = new Line(new Point(1, 1), new Point(2, 2));
+  const b = a.flip();
+  test.equals(b.p1, a.p2);
+  test.equals(b.p2, a.p1);
+
+  test.end();
+});
\ No newline at end of file