diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 91c77d6..bb78b4f 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -63,3 +63,11 @@ parameters:
             message: "#^Calling sha1\\(\\) is forbidden, use hash\\(\\) with at least SHA\\-256 for secure hash, or password_hash\\(\\) for passwords\\.$#"
             count: 1
             path: src/FileUploadControl/Storage/Metadata/FileUploadMetadata.php
+        - # false-positive
+            message: "#^Method Nepada\\\\FileUploadControl\\\\Storage\\\\ContentRange\\:\\:getRangeSize\\(\\) should return int\\<0, max\\> but returns int\\.$#"
+            count: 1
+            path: src/FileUploadControl/Storage/ContentRange.php
+        - # should not happen
+            message: "#^Parameter \\#1 \\$size of static method Nepada\\\\FileUploadControl\\\\Storage\\\\ContentRange\\:\\:ofSize\\(\\) expects int\\<0, max\\>, int given\\.$#"
+            count: 1
+            path: src/FileUploadControl/Storage/FileUploadChunk.php
diff --git a/src/FileUploadControl/Storage/ContentRange.php b/src/FileUploadControl/Storage/ContentRange.php
index 729ee3d..ea66d81 100644
--- a/src/FileUploadControl/Storage/ContentRange.php
+++ b/src/FileUploadControl/Storage/ContentRange.php
@@ -11,10 +11,19 @@ final class ContentRange
 
     use Nette\SmartObject;
 
+    /**
+     * @var int<0, max>
+     */
     private int $start;
 
+    /**
+     * @var int<0, max>
+     */
     private int $end;
 
+    /**
+     * @var int<0, max>
+     */
     private int $size;
 
     private function __construct(int $start, int $end, int $size)
@@ -25,17 +34,23 @@ private function __construct(int $start, int $end, int $size)
         if ($end < $start) {
             throw new \InvalidArgumentException("Start ($start) cannot be larger than end ($end).");
         }
-        if ($size <= $end) {
-            throw new \InvalidArgumentException("End ($end) cannot be larger or equal to size ($size).");
+        if ($size < $end) {
+            throw new \InvalidArgumentException("End ($end) cannot be larger than size ($size).");
+        }
+        if ($size > 0 && $size === $end) {
+            throw new \InvalidArgumentException("End ($end) cannot be equal to size ($size).");
         }
         $this->start = $start;
         $this->end = $end;
         $this->size = $size;
     }
 
+    /**
+     * @param int<0, max> $size
+     */
     public static function ofSize(int $size): self
     {
-        return new self(0, $size - 1, $size);
+        return new self(0, $size === 0 ? 0 : $size - 1, $size);
     }
 
     public static function fromHttpHeaderValue(string $header): self
@@ -47,21 +62,33 @@ public static function fromHttpHeaderValue(string $header): self
         return new self((int) $match[1], (int) $match[2], (int) $match[3]);
     }
 
+    /**
+     * @return int<0, max>
+     */
     public function getStart(): int
     {
         return $this->start;
     }
 
+    /**
+     * @return int<0, max>
+     */
     public function getEnd(): int
     {
         return $this->end;
     }
 
+    /**
+     * @return int<0, max>
+     */
     public function getRangeSize(): int
     {
-        return $this->end - $this->start + 1;
+        return $this->size === 0 ? 0 : $this->end - $this->start + 1;
     }
 
+    /**
+     * @return int<0, max>
+     */
     public function getSize(): int
     {
         return $this->size;
@@ -74,7 +101,7 @@ public function containsFirstByte(): bool
 
     public function containsLastByte(): bool
     {
-        return $this->end === ($this->size - 1);
+        return $this->end === max(0, ($this->size - 1));
     }
 
 }
diff --git a/tests/FileUploadControl/Storage/ContentRangeTest.phpt b/tests/FileUploadControl/Storage/ContentRangeTest.phpt
index 110504b..b138cd9 100644
--- a/tests/FileUploadControl/Storage/ContentRangeTest.phpt
+++ b/tests/FileUploadControl/Storage/ContentRangeTest.phpt
@@ -16,6 +16,28 @@ require_once __DIR__ . '/../../bootstrap.php';
 class ContentRangeTest extends TestCase
 {
 
+    public function testOfZeroSize(): void
+    {
+        $contentRange = ContentRange::ofSize(0);
+        Assert::same(0, $contentRange->getSize());
+        Assert::same(0, $contentRange->getStart());
+        Assert::same(0, $contentRange->getEnd());
+        Assert::same(0, $contentRange->getRangeSize());
+        Assert::true($contentRange->containsFirstByte());
+        Assert::true($contentRange->containsLastByte());
+    }
+
+    public function testOfOneByteSize(): void
+    {
+        $contentRange = ContentRange::ofSize(1);
+        Assert::same(1, $contentRange->getSize());
+        Assert::same(0, $contentRange->getStart());
+        Assert::same(0, $contentRange->getEnd());
+        Assert::same(1, $contentRange->getRangeSize());
+        Assert::true($contentRange->containsFirstByte());
+        Assert::true($contentRange->containsLastByte());
+    }
+
     public function testOfSize(): void
     {
         $contentRange = ContentRange::ofSize(42);
@@ -62,9 +84,13 @@ class ContentRangeTest extends TestCase
                 'headerValue' => 'bflmpsvz',
                 'expectedError' => "Malformed content-range header 'bflmpsvz'.",
             ],
+            [
+                'headerValue' => 'bytes 0-10/5',
+                'expectedError' => 'End (10) cannot be larger than size (5).',
+            ],
             [
                 'headerValue' => 'bytes 0-10/10',
-                'expectedError' => 'End (10) cannot be larger or equal to size (10).',
+                'expectedError' => 'End (10) cannot be equal to size (10).',
             ],
             [
                 'headerValue' => 'bytes 10-5/10',