diff --git a/src/Progressable.php b/src/Progressable.php
index 4492077..d53f833 100644
--- a/src/Progressable.php
+++ b/src/Progressable.php
@@ -292,23 +292,33 @@ public function isOverallComplete(): bool {
      * Get the estimated time remaining in seconds for the overall progress.
      */
     public function getOverallEstimatedTimeRemaining(): ?int {
-        $overallProgress = $this->getOverallProgress();
-
-        if ($overallProgress >= 100) {
-            return 0;
-        }
-
         $progressData = $this->getOverallProgressData();
 
         if (empty($progressData)) {
             return null;
         }
 
+        $totalProgress = 0;
+        $allComplete = true;
+
+        foreach ($progressData as $data) {
+            $progress = $data['progress'] ?? 0;
+            $totalProgress += $progress;
+
+            if ($progress < 100) {
+                $allComplete = false;
+            }
+        }
+
+        if ($allComplete) {
+            return 0;
+        }
+
         $startTimes = array_filter(array_column($progressData, 'start_time'), function ($time) {
             return $time !== null;
         });
 
-        if (empty($startTimes) || $overallProgress <= 0) {
+        if (empty($startTimes) || $totalProgress <= 0) {
             return null;
         }
 
@@ -319,6 +329,12 @@ public function getOverallEstimatedTimeRemaining(): ?int {
             return null;
         }
 
+        $overallProgress = $totalProgress / count($progressData);
+
+        if ($overallProgress <= 0) {
+            return null;
+        }
+
         $rate = $overallProgress / $elapsed;
         $remainingProgress = 100 - $overallProgress;
 
diff --git a/tests/IsCompleteBugTest.php b/tests/IsCompleteBugTest.php
new file mode 100644
index 0000000..d371f7b
--- /dev/null
+++ b/tests/IsCompleteBugTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Verseles\Progressable\Tests;
+
+use Orchestra\Testbench\TestCase;
+use Verseles\Progressable\Progressable;
+
+class DummyProgressableCompleteBug {
+    use Progressable;
+}
+
+class IsCompleteBugTest extends TestCase {
+    public function test_is_complete_does_not_return_true_prematurely() {
+        $a = new DummyProgressableCompleteBug;
+        $a->setPrecision(0);
+        $a->setOverallUniqueName('test_complete_bug');
+        $a->setLocalKey('a');
+        $a->setLocalProgress(99.6); // getLocalProgress() will return 100
+
+        $this->assertEquals(100, $a->getLocalProgress());
+        $this->assertFalse($a->isComplete(), 'isComplete should return false when progress < 100, even if rounded to 100.');
+
+        $a->setLocalProgress(100);
+        $this->assertTrue($a->isComplete(), 'isComplete should return true when progress is 100.');
+    }
+}
diff --git a/tests/OverallEtaBugTest.php b/tests/OverallEtaBugTest.php
new file mode 100644
index 0000000..728b695
--- /dev/null
+++ b/tests/OverallEtaBugTest.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace Verseles\Progressable\Tests;
+
+use Illuminate\Support\Carbon;
+use Orchestra\Testbench\TestCase;
+use Verseles\Progressable\Progressable;
+
+class DummyProgressableOverallEtaBug {
+    use Progressable;
+}
+
+class OverallEtaBugTest extends TestCase {
+    public function test_overall_eta_calculation_with_long_elapsed_time() {
+        Carbon::setTestNow(Carbon::now());
+
+        $uniqueName = 'test_eta_bug_long_' . uniqid();
+
+        $a = new DummyProgressableOverallEtaBug;
+        $a->setPrecision(0);
+        $a->setOverallUniqueName($uniqueName);
+        $a->setLocalKey('a');
+        $a->setLocalProgress(100);
+
+        Carbon::setTestNow(Carbon::now()->addSeconds(1000));
+
+        $b = new DummyProgressableOverallEtaBug;
+        $b->setPrecision(0);
+        $b->setOverallUniqueName($uniqueName);
+        $b->setLocalKey('b');
+        // We want average progress to round to 100 with PHP_ROUND_HALF_ODD.
+        // 99.6 rounds to 100.
+        // a=100. Let b=99.2. Average = 99.6. getOverallProgress(0) = 100.
+        // Unrounded average = 99.6.
+        // Rate = 99.6 / 1000 = 0.0996.
+        // Remaining = 100 - 99.6 = 0.4.
+        // ETA = 0.4 / 0.0996 = 4.016 -> rounds to 4.
+        $b->setLocalProgress(99.2);
+
+        $this->assertEquals(100, $a->getOverallProgress());
+        $this->assertFalse($a->isOverallComplete());
+
+        $eta = $a->getOverallEstimatedTimeRemaining();
+        $this->assertEquals(4, $eta, 'ETA should calculate correctly from unrounded progress, yielding 4 seconds.');
+    }
+}