diff --git a/CHANGELOG.md b/CHANGELOG.md
index aebe2573..f688ef67 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@
 ### Maintenance
 - Added testing with SSL connection (#1624)
 - Added testing with SSL authentication using CN (#1627)
+- Added testing with TimeSeries NaN values (#1628)
 - Added support for Redis 8.6 (#1631)
 
 ## v3.3.0 (2025-11-24)
diff --git a/src/ClientContextInterface.php b/src/ClientContextInterface.php
index 68187529..29a38d1f 100644
--- a/src/ClientContextInterface.php
+++ b/src/ClientContextInterface.php
@@ -272,7 +272,7 @@ use Predis\Command\Redis\VADD;
  * @method $this topklist(string $key, bool $withCount = false)
  * @method $this topkquery(string $key, ...$items)
  * @method $this topkreserve(string $key, int $topK, int $width = 8, int $depth = 7, float $decay = 0.9)
- * @method $this tsadd(string $key, int $timestamp, float $value, ?AddArguments $arguments = null)
+ * @method $this tsadd(string $key, int $timestamp, string|float $value, ?AddArguments $arguments = null)
  * @method $this tsalter(string $key, ?TSAlterArguments $arguments = null)
  * @method $this tscreate(string $key, ?TSCreateArguments $arguments = null)
  * @method $this tscreaterule(string $sourceKey, string $destKey, string $aggregator, int $bucketDuration, int $alignTimestamp = 0)
diff --git a/src/ClientInterface.php b/src/ClientInterface.php
index 9abeadb5..bb3424e2 100644
--- a/src/ClientInterface.php
+++ b/src/ClientInterface.php
@@ -283,7 +283,7 @@ use Predis\Response\Status;
  * @method array             topklist(string $key, bool $withCount = false)
  * @method array             topkquery(string $key, ...$items)
  * @method Status            topkreserve(string $key, int $topK, int $width = 8, int $depth = 7, float $decay = 0.9)
- * @method int               tsadd(string $key, int $timestamp, float $value, ?AddArguments $arguments = null)
+ * @method int               tsadd(string $key, int $timestamp, string|float $value, ?AddArguments $arguments = null)
  * @method Status            tsalter(string $key, ?TSAlterArguments $arguments = null)
  * @method Status            tscreate(string $key, ?TSCreateArguments $arguments = null)
  * @method Status            tscreaterule(string $sourceKey, string $destKey, string $aggregator, int $bucketDuration, int $alignTimestamp = 0)
diff --git a/src/Command/Argument/TimeSeries/RangeArguments.php b/src/Command/Argument/TimeSeries/RangeArguments.php
index 6828a7d4..224f0603 100644
--- a/src/Command/Argument/TimeSeries/RangeArguments.php
+++ b/src/Command/Argument/TimeSeries/RangeArguments.php
@@ -14,6 +14,13 @@ namespace Predis\Command\Argument\TimeSeries;
 
 class RangeArguments extends CommonArguments
 {
+    public const AGG_SUM = 'sum';
+    public const AGG_MIN = 'min';
+    public const AGG_MAX = 'max';
+    public const AGG_COUNT = 'count';
+    public const AGG_COUNT_NAN = 'countNan';
+    public const AGG_COUNT_ALL = 'countAll';
+
     /**
      * Filters samples by a list of specific timestamps.
      *
@@ -57,7 +64,7 @@ class RangeArguments extends CommonArguments
     /**
      * Aggregates samples into time buckets.
      *
-     * @param  string $aggregator
+     * @param  string $aggregator      Aggregation type. Check class constants.
      * @param  int    $bucketDuration  Is duration of each bucket, in milliseconds.
      * @param  int    $align           It controls the time bucket timestamps by changing the reference timestamp on which a bucket is defined.
      * @param  int    $bucketTimestamp Controls how bucket timestamps are reported.
diff --git a/tests/Predis/Command/Argument/TimeSeries/RangeArgumentsTest.php b/tests/Predis/Command/Argument/TimeSeries/RangeArgumentsTest.php
index 4326ce91..23258455 100644
--- a/tests/Predis/Command/Argument/TimeSeries/RangeArgumentsTest.php
+++ b/tests/Predis/Command/Argument/TimeSeries/RangeArgumentsTest.php
@@ -73,24 +73,24 @@ class RangeArgumentsTest extends TestCase
     {
         return [
             'with default arguments' => [
-                ['sum', 1000],
-                ['AGGREGATION', 'sum', 1000],
+                [RangeArguments::AGG_SUM, 1000],
+                ['AGGREGATION', RangeArguments::AGG_SUM, 1000],
             ],
             'with ALIGN modifier' => [
-                ['sum', 1000, 10],
-                ['ALIGN', 10, 'AGGREGATION', 'sum', 1000],
+                [RangeArguments::AGG_COUNT, 1000, 10],
+                ['ALIGN', 10, 'AGGREGATION', RangeArguments::AGG_COUNT, 1000],
             ],
             'with BUCKETTIMESTAMP modifier' => [
-                ['sum', 1000, 0, 10000],
-                ['AGGREGATION', 'sum', 1000, 'BUCKETTIMESTAMP', 10000],
+                [RangeArguments::AGG_MAX, 1000, 0, 10000],
+                ['AGGREGATION', RangeArguments::AGG_MAX, 1000, 'BUCKETTIMESTAMP', 10000],
             ],
             'with EMPTY modifier' => [
-                ['sum', 1000, 0, 0, true],
-                ['AGGREGATION', 'sum', 1000, 'EMPTY'],
+                [RangeArguments::AGG_MIN, 1000, 0, 0, true],
+                ['AGGREGATION', RangeArguments::AGG_MIN, 1000, 'EMPTY'],
             ],
             'with all arguments' => [
-                ['sum', 1000, 10, 10000, true],
-                ['ALIGN', 10, 'AGGREGATION', 'sum', 1000, 'BUCKETTIMESTAMP', 10000, 'EMPTY'],
+                [RangeArguments::AGG_COUNT_NAN, 1000, 10, 10000, true],
+                ['ALIGN', 10, 'AGGREGATION', RangeArguments::AGG_COUNT_NAN, 1000, 'BUCKETTIMESTAMP', 10000, 'EMPTY'],
             ],
         ];
     }
diff --git a/tests/Predis/Command/Redis/TimeSeries/TSMRANGE_Test.php b/tests/Predis/Command/Redis/TimeSeries/TSMRANGE_Test.php
index ddf7a549..6722f586 100644
--- a/tests/Predis/Command/Redis/TimeSeries/TSMRANGE_Test.php
+++ b/tests/Predis/Command/Redis/TimeSeries/TSMRANGE_Test.php
@@ -12,8 +12,10 @@
 
 namespace Predis\Command\Redis\TimeSeries;
 
+use Predis\Command\Argument\TimeSeries\CommonArguments;
 use Predis\Command\Argument\TimeSeries\CreateArguments;
 use Predis\Command\Argument\TimeSeries\MRangeArguments;
+use Predis\Command\Argument\TimeSeries\RangeArguments;
 use Predis\Command\Redis\PredisCommandTestCase;
 
 /**
@@ -154,6 +156,76 @@ class TSMRANGE_Test extends PredisCommandTestCase
         $this->assertEquals($expectedResponse, $redis->tsmrange('-', '+', $mrangeArguments));
     }
 
+    /**
+     * @group connected
+     * @group relay-resp3
+     * @return void
+     * @requiresRedisVersion >= 8.5.0
+     */
+    public function testAddSamplesIntoFewTimeSeriesWithNaNValues(): void
+    {
+        $redis = $this->getClient();
+
+        $createArguments = (new CreateArguments())
+            ->retentionMsecs(60000)
+            ->duplicatePolicy(CommonArguments::POLICY_MAX)
+            ->labels('type', 'temperature', 'name', 'A');
+
+        $this->assertEquals(
+            'OK',
+            $redis->tscreate('temperature:A', $createArguments)
+        );
+
+        $createArguments = (new CreateArguments())
+            ->retentionMsecs(60000)
+            ->duplicatePolicy(CommonArguments::POLICY_MAX)
+            ->labels('type', 'temperature', 'name', 'B');
+
+        $this->assertEquals(
+            'OK',
+            $redis->tscreate('temperature:B', $createArguments)
+        );
+
+        // Add NaN value samples
+        $this->assertEquals(
+            [1000, 1001],
+            $redis->tsmadd(
+                'temperature:A', 1000, 'NaN', 'temperature:A', 1001, 27
+            )
+        );
+
+        $this->assertEquals(
+            [1000, 1001],
+            $redis->tsmadd(
+                'temperature:B', 1000, 'NaN', 'temperature:B', 1001, 28
+            )
+        );
+
+        // Ensure that we can count all values (included NaN)
+        $mRangeArguments = (new MRangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_ALL, 1000)
+            ->filter('type=temperature');
+
+        $expectedResponse = [
+            ['temperature:A', [], [[1000, 2]]],
+            ['temperature:B', [], [[1000, 2]]],
+        ];
+
+        $this->assertEquals($expectedResponse, $redis->tsmrange(1000, 1001, $mRangeArguments));
+
+        // Ensure that we can count NaN values only
+        $mRangeArguments = (new MRangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_NAN, 1000)
+            ->filter('type=temperature');
+
+        $expectedResponse = [
+            ['temperature:A', [], [[1000, 1]]],
+            ['temperature:B', [], [[1000, 1]]],
+        ];
+
+        $this->assertEquals($expectedResponse, $redis->tsmrange(1000, 1001, $mRangeArguments));
+    }
+
     public function argumentsProvider(): array
     {
         return [
diff --git a/tests/Predis/Command/Redis/TimeSeries/TSMREVRANGE_Test.php b/tests/Predis/Command/Redis/TimeSeries/TSMREVRANGE_Test.php
index 9bd8a000..4c89a728 100644
--- a/tests/Predis/Command/Redis/TimeSeries/TSMREVRANGE_Test.php
+++ b/tests/Predis/Command/Redis/TimeSeries/TSMREVRANGE_Test.php
@@ -12,8 +12,10 @@
 
 namespace Predis\Command\Redis\TimeSeries;
 
+use Predis\Command\Argument\TimeSeries\CommonArguments;
 use Predis\Command\Argument\TimeSeries\CreateArguments;
 use Predis\Command\Argument\TimeSeries\MRangeArguments;
+use Predis\Command\Argument\TimeSeries\RangeArguments;
 use Predis\Command\Redis\PredisCommandTestCase;
 
 /**
@@ -154,6 +156,76 @@ class TSMREVRANGE_Test extends PredisCommandTestCase
         $this->assertEquals($expectedResponse, $redis->tsmrevrange('-', '+', $mrangeArguments));
     }
 
+    /**
+     * @group connected
+     * @group relay-resp3
+     * @return void
+     * @requiresRedisVersion >= 8.5.0
+     */
+    public function testAddSamplesIntoFewTimeSeriesWithNaNValues(): void
+    {
+        $redis = $this->getClient();
+
+        $createArguments = (new CreateArguments())
+            ->retentionMsecs(60000)
+            ->duplicatePolicy(CommonArguments::POLICY_MAX)
+            ->labels('type', 'temperature', 'name', 'A');
+
+        $this->assertEquals(
+            'OK',
+            $redis->tscreate('temperature:A', $createArguments)
+        );
+
+        $createArguments = (new CreateArguments())
+            ->retentionMsecs(60000)
+            ->duplicatePolicy(CommonArguments::POLICY_MAX)
+            ->labels('type', 'temperature', 'name', 'B');
+
+        $this->assertEquals(
+            'OK',
+            $redis->tscreate('temperature:B', $createArguments)
+        );
+
+        // Add NaN value samples
+        $this->assertEquals(
+            [1000, 1001],
+            $redis->tsmadd(
+                'temperature:A', 1000, 'NaN', 'temperature:A', 1001, 27
+            )
+        );
+
+        $this->assertEquals(
+            [1000, 1001],
+            $redis->tsmadd(
+                'temperature:B', 1000, 'NaN', 'temperature:B', 1001, 28
+            )
+        );
+
+        // Ensure that we can count all values (included NaN)
+        $mRangeArguments = (new MRangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_ALL, 1000)
+            ->filter('type=temperature');
+
+        $expectedResponse = [
+            ['temperature:A', [], [[1000, 2]]],
+            ['temperature:B', [], [[1000, 2]]],
+        ];
+
+        $this->assertEquals($expectedResponse, $redis->tsmrevrange(1000, 1001, $mRangeArguments));
+
+        // Ensure that we can count NaN values only
+        $mRangeArguments = (new MRangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_NAN, 1000)
+            ->filter('type=temperature');
+
+        $expectedResponse = [
+            ['temperature:A', [], [[1000, 1]]],
+            ['temperature:B', [], [[1000, 1]]],
+        ];
+
+        $this->assertEquals($expectedResponse, $redis->tsmrevrange(1000, 1001, $mRangeArguments));
+    }
+
     public function argumentsProvider(): array
     {
         return [
diff --git a/tests/Predis/Command/Redis/TimeSeries/TSRANGE_Test.php b/tests/Predis/Command/Redis/TimeSeries/TSRANGE_Test.php
index f34ffc7f..a452f396 100644
--- a/tests/Predis/Command/Redis/TimeSeries/TSRANGE_Test.php
+++ b/tests/Predis/Command/Redis/TimeSeries/TSRANGE_Test.php
@@ -12,6 +12,7 @@
 
 namespace Predis\Command\Redis\TimeSeries;
 
+use Predis\Command\Argument\TimeSeries\CommonArguments;
 use Predis\Command\Argument\TimeSeries\CreateArguments;
 use Predis\Command\Argument\TimeSeries\RangeArguments;
 use Predis\Command\PrefixableCommand;
@@ -126,6 +127,63 @@ class TSRANGE_Test extends PredisCommandTestCase
         );
     }
 
+    /**
+     * @group connected
+     * @group relay-resp3
+     * @return void
+     * @requiresRedisVersion >= 8.5.0
+     */
+    public function testAddSampleIntoTimeSeriesWithNaNValues(): void
+    {
+        $redis = $this->getClient();
+
+        $createArguments = (new CreateArguments())
+            ->retentionMsecs(31536000000)
+            ->duplicatePolicy(CommonArguments::POLICY_LAST)
+            ->ignore(10, 10);
+
+        $this->assertEquals('OK', $redis->tscreate('temperature:2:32', $createArguments));
+
+        // Add NaN value samples
+        $this->assertEquals(
+            1000,
+            $redis->tsadd('temperature:2:32', 1000, 'NaN')
+        );
+
+        $this->assertEquals(
+            1003,
+            $redis->tsadd('temperature:2:32', 1003, 25)
+        );
+
+        $this->assertEquals(
+            1005,
+            $redis->tsadd('temperature:2:32', 1005, 'NaN')
+        );
+
+        $this->assertEquals(
+            1006,
+            $redis->tsadd('temperature:2:32', 1006, 'NaN')
+        );
+
+        // Ensure that we can count NaN values only
+        $rangeArguments = (new RangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_NAN, 1000);
+
+        $this->assertEquals(
+            [[1000, 3]],
+            $redis->tsrange('temperature:2:32', 1000, 1006, $rangeArguments)
+        );
+
+        // Ensure that we can count all values (included NaN)
+        $rangeArguments = (new RangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_ALL, 1000);
+
+        $this->assertEquals(
+            [[1000, 4]],
+            $redis->tsrange('temperature:2:32', 1000, 1006, $rangeArguments)
+        );
+    }
+
     /**
      * @group connected
      * @group relay-resp3
diff --git a/tests/Predis/Command/Redis/TimeSeries/TSREVRANGE_Test.php b/tests/Predis/Command/Redis/TimeSeries/TSREVRANGE_Test.php
index 3d40d1af..cb594d9a 100644
--- a/tests/Predis/Command/Redis/TimeSeries/TSREVRANGE_Test.php
+++ b/tests/Predis/Command/Redis/TimeSeries/TSREVRANGE_Test.php
@@ -12,6 +12,7 @@
 
 namespace Predis\Command\Redis\TimeSeries;
 
+use Predis\Command\Argument\TimeSeries\CommonArguments;
 use Predis\Command\Argument\TimeSeries\CreateArguments;
 use Predis\Command\Argument\TimeSeries\RangeArguments;
 use Predis\Command\PrefixableCommand;
@@ -126,6 +127,63 @@ class TSREVRANGE_Test extends PredisCommandTestCase
         );
     }
 
+    /**
+     * @group connected
+     * @group relay-resp3
+     * @return void
+     * @requiresRedisVersion >= 8.5.0
+     */
+    public function testAddSampleIntoTimeSeriesWithNaNValues(): void
+    {
+        $redis = $this->getClient();
+
+        $createArguments = (new CreateArguments())
+            ->retentionMsecs(31536000000)
+            ->duplicatePolicy(CommonArguments::POLICY_LAST)
+            ->ignore(10, 10);
+
+        $this->assertEquals('OK', $redis->tscreate('temperature:2:32', $createArguments));
+
+        // Add NaN value samples
+        $this->assertEquals(
+            1000,
+            $redis->tsadd('temperature:2:32', 1000, 'NaN')
+        );
+
+        $this->assertEquals(
+            1003,
+            $redis->tsadd('temperature:2:32', 1003, 25)
+        );
+
+        $this->assertEquals(
+            1005,
+            $redis->tsadd('temperature:2:32', 1005, 'NaN')
+        );
+
+        $this->assertEquals(
+            1006,
+            $redis->tsadd('temperature:2:32', 1006, 'NaN')
+        );
+
+        // Ensure that we can count NaN values only
+        $rangeArguments = (new RangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_NAN, 1000);
+
+        $this->assertEquals(
+            [[1000, 3]],
+            $redis->tsrevrange('temperature:2:32', 1000, 1006, $rangeArguments)
+        );
+
+        // Ensure that we can count all values (included NaN)
+        $rangeArguments = (new RangeArguments())
+            ->aggregation(RangeArguments::AGG_COUNT_ALL, 1000);
+
+        $this->assertEquals(
+            [[1000, 4]],
+            $redis->tsrevrange('temperature:2:32', 1000, 1006, $rangeArguments)
+        );
+    }
+
     /**
      * @group connected
      * @group relay-resp3