diff --git a/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/FileJs.kt b/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/FileJs.kt
index e8ba9a6..77db7fa 100644
--- a/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/FileJs.kt
+++ b/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/FileJs.kt
@@ -51,14 +51,8 @@ public fun File.write(data: Buffer) {
 public fun Throwable.toIOException(): IOException {
     if (this is IOException) return this
 
-    val code = try {
-        errorCode
-    } catch (_: Throwable) {
-        null
-    }
-
-    return when (code) {
+    return when (errorCode) {
         "ENOENT" -> FileNotFoundException(message)
-        else -> IOException(message)
+        else -> IOException(this)
     }
 }
diff --git a/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/Wrappers.kt b/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/Wrappers.kt
index 57ce706..c1cfb1f 100644
--- a/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/Wrappers.kt
+++ b/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/Wrappers.kt
@@ -16,6 +16,7 @@
 package io.matthewnelson.kmp.file
 
 import io.matthewnelson.kmp.file.internal.buffer_Buffer
+import io.matthewnelson.kmp.file.internal.errorCode
 import io.matthewnelson.kmp.file.internal.fs_Stats
 
 /**
@@ -34,22 +35,20 @@ public value class Buffer internal constructor(
     public val length: Long get() = value.length.toLong()
     public fun fill() { value.fill() }
 
-    // @Throws(IOException::class)
+    // @Throws(IndexOutOfBoundsException::class, IllegalArgumentException::class)
     public fun readInt8(index: Number): Byte = try {
         value.readInt8(index) as Byte
     } catch (t: Throwable) {
-        throw t.toIOException()
+        throw when (t.errorCode) {
+            "ERR_OUT_OF_RANGE" -> IndexOutOfBoundsException(t.message)
+            else -> IllegalArgumentException(t)
+        }
     }
 
-    // @Throws(IOException::class)
     public fun toUtf8(
         start: Number = 0,
         end: Number = this.length,
-    ): String = try {
-        value.toString("utf8", start, end)
-    } catch (t: Throwable) {
-        throw t.toIOException()
-    }
+    ): String = value.toString("utf8", start, end)
 
     public fun unwrap(): dynamic = value.asDynamic()
 
@@ -57,10 +56,10 @@ public value class Buffer internal constructor(
 
     public companion object {
 
-        // @Throws(IOException::class)
+        // @Throws(IllegalArgumentException::class)
         public fun wrap(buffer: dynamic): Buffer {
             if (!buffer_Buffer.isBuffer(buffer)) {
-                throw IOException("Not a buffer")
+                throw IllegalArgumentException("Not a buffer")
             }
 
             return Buffer(buffer.unsafeCast<buffer_Buffer>())
diff --git a/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/internal/JsPlatform.kt b/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/internal/JsPlatform.kt
index f2415b2..c8ca7f8 100644
--- a/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/internal/JsPlatform.kt
+++ b/library/file/src/jsMain/kotlin/io/matthewnelson/kmp/file/internal/JsPlatform.kt
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  **/
-@file:Suppress("FunctionName", "ACTUAL_ANNOTATIONS_NOT_MATCH_EXPECT")
+@file:Suppress("FunctionName", "ACTUAL_ANNOTATIONS_NOT_MATCH_EXPECT", "KotlinRedundantDiagnosticSuppress")
 
 package io.matthewnelson.kmp.file.internal
 
@@ -43,6 +43,7 @@ internal actual val IsWindows: Boolean by lazy {
     }
 }
 
+// @Throws(IOException::class)
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun File.platformReadBytes(): ByteArray = try {
     val buffer = read()
@@ -60,6 +61,7 @@ internal actual inline fun File.platformReadBytes(): ByteArray = try {
     throw t.toIOException()
 }
 
+// @Throws(IOException::class)
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun File.platformReadUtf8(): String = try {
     val buffer = read()
@@ -77,6 +79,7 @@ internal actual inline fun File.platformReadUtf8(): String = try {
     throw t.toIOException()
 }
 
+// @Throws(IOException::class)
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun File.platformWriteBytes(array: ByteArray) {
     try {
@@ -86,6 +89,7 @@ internal actual inline fun File.platformWriteBytes(array: ByteArray) {
     }
 }
 
+// @Throws(IOException::class)
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun File.platformWriteUtf8(text: String) {
     try {
@@ -117,6 +121,7 @@ internal actual inline fun Path.isAbsolute(): Boolean {
     return path_isAbsolute(this)
 }
 
+// @Throws(IOException::class)
 internal actual fun fs_chmod(path: String, mode: String) {
     try {
         fs_chmodSync(path, mode)
@@ -125,6 +130,7 @@ internal actual fun fs_chmod(path: String, mode: String) {
     }
 }
 
+// @Throws(IOException::class)
 internal actual fun fs_remove(path: String): Boolean {
     try {
         fs_unlinkSync(path)
@@ -163,6 +169,7 @@ internal actual fun fs_mkdir(path: String): Boolean {
     }
 }
 
+// @Throws(IOException::class)
 internal actual fun fs_realpath(path: String): String {
     return try {
         fs_realpathSync(path)
@@ -171,4 +178,9 @@ internal actual fun fs_realpath(path: String): String {
     }
 }
 
-internal val Throwable.errorCode: dynamic get() = asDynamic().code
+@Suppress("NOTHING_TO_INLINE", "REDUNDANT_NULLABLE")
+internal inline val Throwable.errorCode: String? get() = try {
+    asDynamic().code as String
+} catch (_: Throwable) {
+    null
+}
diff --git a/library/file/src/jsTest/kotlin/io/matthewnelson/kmp/file/WrapperUnitTest.kt b/library/file/src/jsTest/kotlin/io/matthewnelson/kmp/file/WrapperUnitTest.kt
index f46d1ff..5f209c0 100644
--- a/library/file/src/jsTest/kotlin/io/matthewnelson/kmp/file/WrapperUnitTest.kt
+++ b/library/file/src/jsTest/kotlin/io/matthewnelson/kmp/file/WrapperUnitTest.kt
@@ -39,7 +39,7 @@ class WrapperUnitTest {
     @Test
     fun givenBuffer_whenFromDynamicAndNotActuallyABuffer_thenThrowsException() {
         val stats = FILE_LOREM_IPSUM.stat().unwrap()
-        assertFailsWith<IOException> { Buffer.wrap(stats) }
+        assertFailsWith<IllegalArgumentException> { Buffer.wrap(stats) }
     }
 
     @Test