diff --git a/ROADMAP.md b/ROADMAP.md
index 7b67586..ede052d 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -5,7 +5,6 @@
 <details>
   <summary>Show</summary>
 
-* Port tests.
 * Set up code coverage.
 * Port benchmarks.
 * Set up multiplatform benchmarks.
diff --git a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/ByteBufferRadAccessor.kt b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/ByteBufferRadAccessor.kt
index 473d168..8e76243 100644
--- a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/ByteBufferRadAccessor.kt
+++ b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/ByteBufferRadAccessor.kt
@@ -5,6 +5,7 @@
 package fluxo.io.rad
 
 import fluxo.io.internal.Blocking
+import fluxo.io.util.checkOffsetAndCount
 import fluxo.io.util.toIntChecked
 import java.io.File
 import java.io.FileDescriptor
@@ -50,13 +51,15 @@ public fun RadByteBufferAccessor(
 ): RandomAccessData = ByteBufferRad(data, offset = offset, size = size)
 
 
-private fun byteBufferRad0(
+private fun byteBufferMmapRad0(
     channel: FileChannel,
     offset: Long,
     size: Int,
     vararg resources: AutoCloseable,
 ): RandomAccessData {
-    val size0 = if (size == -1) (channel.size() - offset).toIntChecked() else size
+    val dataLength = channel.size()
+    val size0 = if (size == -1) (dataLength - offset).toIntChecked() else size
+    checkOffsetAndCount(dataLength, offset, size0.toLong())
     val byteBuffer = channel.map(MapMode.READ_ONLY, offset, size0.toLong())
     return ByteBufferRad(byteBuffer, offset = 0, size = size0, resources = resources)
 }
@@ -75,7 +78,7 @@ private fun byteBufferRad0(
  *
  * @param data the underlying [FileInputStream]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  *
  * @see java.nio.channels.FileChannel.map
  */
@@ -88,7 +91,7 @@ public fun RadByteBufferAccessor(
     size: Int = -1,
 ): RandomAccessData {
     val channel = data.channel
-    return byteBufferRad0(channel, offset = offset, size = size, channel, data)
+    return byteBufferMmapRad0(channel, offset = offset, size = size, channel, data)
 }
 
 /**
@@ -105,7 +108,7 @@ public fun RadByteBufferAccessor(
  *
  * @param data the underlying [FileChannel]
  * @param offset the offset of the section
- * @param size the length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  *
  * @see java.nio.channels.FileChannel.map
  */
@@ -116,7 +119,7 @@ public fun RadByteBufferAccessor(
     data: FileChannel,
     offset: Long = 0L,
     size: Int = -1,
-): RandomAccessData = byteBufferRad0(data, offset = offset, size = size, data)
+): RandomAccessData = byteBufferMmapRad0(data, offset = offset, size = size, data)
 
 /**
  * Creates a new memory-mapping [ByteBuffer]-based [RandomAccessData] instance
@@ -132,9 +135,7 @@ public fun RadByteBufferAccessor(
  *
  * @param data the underlying [File]
  * @param offset the offset of the section
- * @param size the length of the section
- *
- * @TODO: Would it be better to use [FileChannel.size] instead of [File.length]?
+ * @param size the optional length of the section. -1 means the rest of the file.
  *
  * @see java.nio.channels.FileChannel.map
  */
@@ -144,11 +145,11 @@ public fun RadByteBufferAccessor(
 public fun RadByteBufferAccessor(
     data: File,
     offset: Long = 0L,
-    size: Int = (data.length() - offset).toIntChecked(),
+    size: Int = -1,
 ): RandomAccessData {
     val stream = FileInputStream(data)
     val channel = stream.channel
-    return byteBufferRad0(channel, offset = offset, size = size, channel, stream)
+    return byteBufferMmapRad0(channel, offset = offset, size = size, channel, stream)
 }
 
 /**
@@ -165,7 +166,7 @@ public fun RadByteBufferAccessor(
  *
  * @param data the underlying [FileDescriptor]
  * @param offset the offset of the section
- * @param size the length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  *
  * @see java.nio.channels.FileChannel.map
  */
@@ -179,7 +180,7 @@ public fun RadByteBufferAccessor(
 ): RandomAccessData {
     val stream = FileInputStream(data)
     val channel = stream.channel
-    return byteBufferRad0(channel, offset = offset, size = size, channel, stream)
+    return byteBufferMmapRad0(channel, offset = offset, size = size, channel, stream)
 }
 
 
diff --git a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/FileChannelRadAccessor.kt b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/FileChannelRadAccessor.kt
index b56615b..3bb3642 100644
--- a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/FileChannelRadAccessor.kt
+++ b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/FileChannelRadAccessor.kt
@@ -19,7 +19,7 @@ import java.nio.channels.FileChannel
  *
  * @param data the underlying [FileChannel]
  * @param offset the offset of the section
- * @param size the length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  * @param resources the optional resources to close when finished
  */
 @Blocking
@@ -44,7 +44,7 @@ public fun RadFileChannelAccessor(
  *
  * @param data the underlying [FileInputStream]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
@@ -67,9 +67,7 @@ public fun RadFileChannelAccessor(
  *
  * @param data the underlying [File]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
- *
- * @TODO: Would it be better to use [FileChannel.size] instead of [File.length]?
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
@@ -77,7 +75,7 @@ public fun RadFileChannelAccessor(
 public fun RadFileChannelAccessor(
     data: File,
     offset: Long = 0L,
-    size: Long = data.length() - offset,
+    size: Long = -1L,
 ): RandomAccessData = RadFileChannelAccessor(FileInputStream(data), offset = offset, size = size)
 
 /**
@@ -89,7 +87,7 @@ public fun RadFileChannelAccessor(
  *
  * @param data the underlying [FileDescriptor]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
diff --git a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/RandomAccessFileRadAccessor.kt b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/RandomAccessFileRadAccessor.kt
index b532002..6075b6c 100644
--- a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/RandomAccessFileRadAccessor.kt
+++ b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/RandomAccessFileRadAccessor.kt
@@ -5,6 +5,7 @@
 package fluxo.io.rad
 
 import fluxo.io.internal.Blocking
+import fluxo.io.util.checkOffsetAndCount
 import java.io.File
 import java.io.FileNotFoundException
 import java.io.RandomAccessFile
@@ -21,7 +22,7 @@ import java.io.RandomAccessFile
  *
  * @param data the underlying [RandomAccessFile]
  * @param offset the offset of the section
- * @param size the length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
@@ -31,7 +32,9 @@ public fun RandomAccessFileRadAccessor(
     offset: Long = 0L,
     size: Long = -1L,
 ): RandomAccessData {
-    val size0 = if (size == -1L) data.length() - offset else size
+    val dataLength = data.length()
+    val size0 = if (size == -1L) dataLength - offset else size
+    checkOffsetAndCount(dataLength, offset, size0)
     return RandomAccessFileRad(data, offset = offset, size = size0)
 }
 
@@ -47,9 +50,7 @@ public fun RandomAccessFileRadAccessor(
  *
  * @param data the underlying [File]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
- *
- * @TODO: Would it be better to use [RandomAccessFile.length] instead of [File.length]?
+ * @param size the optional length of the section. -1 means the rest of the file.
  *
  * @throws IllegalArgumentException if the file doesn't exist
  */
@@ -60,6 +61,6 @@ public fun RandomAccessFileRadAccessor(
 public fun RandomAccessFileRadAccessor(
     data: File,
     offset: Long = 0L,
-    size: Long = data.length() - offset,
+    size: Long = -1L,
 ): RandomAccessData =
     RandomAccessFileRadAccessor(RandomAccessFile(data, "r"), offset = offset, size = size)
diff --git a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/SeekableByteChannelRadAccessor.kt b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/SeekableByteChannelRadAccessor.kt
index 63d40fa..537276c 100644
--- a/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/SeekableByteChannelRadAccessor.kt
+++ b/fluxo-io-rad/src/commonJvmMain/kotlin/fluxo/io/rad/SeekableByteChannelRadAccessor.kt
@@ -5,6 +5,7 @@
 package fluxo.io.rad
 
 import fluxo.io.internal.Blocking
+import fluxo.io.util.checkOffsetAndCount
 import java.io.File
 import java.io.FileDescriptor
 import java.io.FileInputStream
@@ -22,7 +23,7 @@ import java.nio.channels.SeekableByteChannel
  *
  * @param data the underlying [SeekableByteChannel]
  * @param offset the offset of the section
- * @param size the length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  * @param resources the optional resources to close when finished
  *
  * @see java.nio.channels.FileChannel
@@ -37,7 +38,9 @@ public fun RadSeekableByteChannelAccessor(
     size: Long = -1L,
     vararg resources: AutoCloseable = arrayOf(data),
 ): RandomAccessData {
-    val size0 = if (size == -1L) data.size() - offset else size
+    val dataLength = data.size()
+    val size0 = if (size == -1L) dataLength - offset else size
+    checkOffsetAndCount(dataLength, offset, size0)
     return SeekableByteChannelRad(data, offset = offset, size = size0, resources = resources)
 }
 
@@ -53,7 +56,7 @@ public fun RadSeekableByteChannelAccessor(
  *
  * @param data the underlying [FileInputStream]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
@@ -79,9 +82,7 @@ public fun RadSeekableByteChannelAccessor(
  *
  * @param data the underlying [File]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
- *
- * @TODO: Would it be better to use [SeekableByteChannel.size] instead of [File.length]?
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
@@ -89,7 +90,7 @@ public fun RadSeekableByteChannelAccessor(
 public fun RadSeekableByteChannelAccessor(
     data: File,
     offset: Long = 0L,
-    size: Long = data.length() - offset,
+    size: Long = -1L,
 ): RandomAccessData =
     RadSeekableByteChannelAccessor(FileInputStream(data), offset = offset, size = size)
 
@@ -105,7 +106,7 @@ public fun RadSeekableByteChannelAccessor(
  *
  * @param data the underlying [FileDescriptor]
  * @param offset the optional offset of the section
- * @param size the optional length of the section
+ * @param size the optional length of the section. -1 means the rest of the file.
  */
 @Blocking
 @JvmOverloads
diff --git a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataByteBufferTest.kt b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataByteBufferTest.kt
index 0961238..e88d8f5 100644
--- a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataByteBufferTest.kt
+++ b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataByteBufferTest.kt
@@ -58,8 +58,8 @@ internal class RadByteBufferAccessorTest(
 
         assertIOB { RadByteBufferAccessor(tempFile, -1, 0) }
         assertIOB { RadByteBufferAccessor(tempFile, -1, 1) }
-        assertIOB { RadByteBufferAccessor(tempFile, 0, -1) }
-        assertIOB { RadByteBufferAccessor(tempFile, 1, -1) }
+        assertIOB { RadByteBufferAccessor(tempFile, 0, -2) }
+        assertIOB { RadByteBufferAccessor(tempFile, 1, -2) }
         assertIOB { RadByteBufferAccessor(tempFile, BYTES.size + 1L) }
         assertIOB { RadByteBufferAccessor(tempFile, BYTES.size.toLong(), 1) }
         assertIOB { RadByteBufferAccessor(tempFile, BYTES.size + 1L, 1) }
diff --git a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataFileChannelTest.kt b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataFileChannelTest.kt
index 24afd3f..0b2393e 100644
--- a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataFileChannelTest.kt
+++ b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataFileChannelTest.kt
@@ -48,8 +48,8 @@ internal class RandomAccessDataFileChannelTest(
 
         assertIOB { RadFileChannelAccessor(tempFile, -1, 0) }
         assertIOB { RadFileChannelAccessor(tempFile, -1, 1) }
-        assertIOB { RadFileChannelAccessor(tempFile, 0, -1) }
-        assertIOB { RadFileChannelAccessor(tempFile, 1, -1) }
+        assertIOB { RadFileChannelAccessor(tempFile, 0, -2) }
+        assertIOB { RadFileChannelAccessor(tempFile, 1, -2) }
         assertIOB { RadFileChannelAccessor(tempFile, BYTES.size + 1L) }
         assertIOB { RadFileChannelAccessor(tempFile, BYTES.size.toLong(), 1L) }
         assertIOB { RadFileChannelAccessor(tempFile, BYTES.size + 1L, 1L) }
diff --git a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataRafTest.kt b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataRafTest.kt
index c5c7103..b64af80 100644
--- a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataRafTest.kt
+++ b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataRafTest.kt
@@ -44,8 +44,8 @@ internal class RandomAccessDataRafTest(
 
         assertIOB { RandomAccessFileRadAccessor(tempFile, -1, 0) }
         assertIOB { RandomAccessFileRadAccessor(tempFile, -1, 1) }
-        assertIOB { RandomAccessFileRadAccessor(tempFile, 0, -1) }
-        assertIOB { RandomAccessFileRadAccessor(tempFile, 1, -1) }
+        assertIOB { RandomAccessFileRadAccessor(tempFile, 0, -2) }
+        assertIOB { RandomAccessFileRadAccessor(tempFile, 1, -2) }
         assertIOB { RandomAccessFileRadAccessor(tempFile, BYTES.size + 1L) }
         assertIOB { RandomAccessFileRadAccessor(tempFile, BYTES.size.toLong(), 1L) }
         assertIOB { RandomAccessFileRadAccessor(tempFile, BYTES.size + 1L, 1L) }
diff --git a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataSeekByteChannelTest.kt b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataSeekByteChannelTest.kt
index d0a6351..a57a8b1 100644
--- a/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataSeekByteChannelTest.kt
+++ b/fluxo-io-rad/src/jvmTest/kotlin/fluxo/io/rad/RandomAccessDataSeekByteChannelTest.kt
@@ -51,8 +51,8 @@ internal class RadSeekableByteChannelAccessorTest(
 
         assertIOB { RadSeekableByteChannelAccessor(tempFile, -1, 0) }
         assertIOB { RadSeekableByteChannelAccessor(tempFile, -1, 1) }
-        assertIOB { RadSeekableByteChannelAccessor(tempFile, 0, -1) }
-        assertIOB { RadSeekableByteChannelAccessor(tempFile, 1, -1) }
+        assertIOB { RadSeekableByteChannelAccessor(tempFile, 0, -2) }
+        assertIOB { RadSeekableByteChannelAccessor(tempFile, 1, -2) }
         assertIOB { RadSeekableByteChannelAccessor(tempFile, BYTES.size + 1L) }
         assertIOB { RadSeekableByteChannelAccessor(tempFile, BYTES.size.toLong(), 1L) }
         assertIOB { RadSeekableByteChannelAccessor(tempFile, BYTES.size + 1L, 1L) }