diff --git a/src/__tests__/timer.test.ts b/src/__tests__/timer.test.ts
index bc7cfb2..fac4647 100644
--- a/src/__tests__/timer.test.ts
+++ b/src/__tests__/timer.test.ts
@@ -37,3 +37,12 @@ test('Negative time zeroed', () => {
   expect(timer.display()).toBe('0:00');
   expect(timer.flagged()).toBeTrue();
 });
+
+test('No increment after flagging', () => {
+  const timer = new FischerTimer(10000, 20000, 1000);
+  timer.begin();
+  timer.remaining = 0;
+  expect(timer.end()).toBeTrue();
+  expect(timer.display()).toBe('0:00');
+  expect(timer.flagged()).toBeTrue();
+});
diff --git a/src/timer.ts b/src/timer.ts
index f6fb124..f31e7f4 100644
--- a/src/timer.ts
+++ b/src/timer.ts
@@ -47,11 +47,15 @@ export class FischerTimer {
     }
     const delta = performance.now() - this.reference;
     this.reference = null;
-    const flagged = delta > this.remaining;
-    this.remaining = Math.min(
-      this.maximum,
-      this.remaining - delta + this.increment
-    );
+    const flagged = delta >= this.remaining;
+    if (flagged) {
+      this.remaining = 0;
+    } else {
+      this.remaining = Math.min(
+        this.maximum,
+        this.remaining - delta + this.increment
+      );
+    }
     return flagged;
   }
 
@@ -74,6 +78,6 @@ export class FischerTimer {
   }
 
   flagged(): boolean {
-    return this.timeRemaining() < 0;
+    return this.timeRemaining() <= 0;
   }
 }