diff --git a/src/commonMain/kotlin/com/infendro/cli/command/Command.kt b/src/commonMain/kotlin/com/infendro/cli/command/Command.kt
index b0ae597..1690d9f 100644
--- a/src/commonMain/kotlin/com/infendro/cli/command/Command.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/command/Command.kt
@@ -7,11 +7,9 @@ import com.infendro.cli.command.context.ContextParser
 import com.infendro.cli.command.help.DefaultHelpRenderer
 import com.infendro.cli.command.help.HelpRenderer
 import com.infendro.cli.command.option.Option
-import com.infendro.cli.exception.build.*
+import com.infendro.cli.error.build.*
 import com.infendro.cli.parser.*
 import com.infendro.cli.util.Regex
-import com.infendro.cli.util.Regex.ARGUMENT
-import com.infendro.cli.util.Regex.OPTION
 import kotlin.reflect.KProperty
 
 sealed class Command private constructor(
@@ -205,15 +203,11 @@ sealed class Command private constructor(
                     argument.required && last.optional -> throw InvalidArgumentOrder()
                 }
             }
-            if (!argument.name.matches(ARGUMENT)) throw InvalidArgument(argument.name)
         }
 
         private fun validateOption(option: Option<*>) {
             for (name in option.names) {
-                when {
-                    !name.matches(OPTION) -> throw InvalidOption(name)
-                    options.any { name in it.names } -> throw DuplicateOption(name)
-                }
+                if (options.any { name in it.names }) throw DuplicateOption(name)
             }
         }
 
@@ -222,7 +216,7 @@ sealed class Command private constructor(
         }
 
         private fun validateRenderer() {
-            if (_renderer != null) throw Exception() //TODO
+            if (_renderer != null) throw DuplicateRenderer()
         }
 
         private fun validate() {
diff --git a/src/commonMain/kotlin/com/infendro/cli/command/argument/Argument.kt b/src/commonMain/kotlin/com/infendro/cli/command/argument/Argument.kt
index 489d35c..3a63920 100644
--- a/src/commonMain/kotlin/com/infendro/cli/command/argument/Argument.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/command/argument/Argument.kt
@@ -1,7 +1,9 @@
 package com.infendro.cli.command.argument
 
-import com.infendro.cli.exception.build.InvalidRange
+import com.infendro.cli.error.build.InvalidArgument
+import com.infendro.cli.error.build.InvalidRange
 import com.infendro.cli.parser.Parser
+import com.infendro.cli.util.Regex.ARGUMENT
 
 sealed class Argument<T : Any>(
     val parser: Parser<T>,
@@ -10,7 +12,10 @@ sealed class Argument<T : Any>(
     val max: Int?,
 ) {
     init {
-        if (min !in 0..count || max == 0) throw InvalidRange()
+        when {
+            !name.matches(ARGUMENT) -> throw InvalidArgument(name)
+            min !in 0..count || max == 0 -> throw InvalidRange()
+        }
     }
 
     val required: Boolean
diff --git a/src/commonMain/kotlin/com/infendro/cli/command/context/ContextParser.kt b/src/commonMain/kotlin/com/infendro/cli/command/context/ContextParser.kt
index 07b6795..4caf619 100644
--- a/src/commonMain/kotlin/com/infendro/cli/command/context/ContextParser.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/command/context/ContextParser.kt
@@ -1,7 +1,7 @@
 package com.infendro.cli.command.context
 
 import com.infendro.cli.command.Command
-import com.infendro.cli.exception.run.*
+import com.infendro.cli.error.run.*
 import com.infendro.cli.parser.Parser
 
 internal class ContextParser(
@@ -19,13 +19,13 @@ internal class ContextParser(
 
         data class Failure(
             val command: Command,
-            val error: RuntimeError,
+            val error: RunError,
         ) : Result()
     }
 
     private fun success(context: Context) = Result.Success(context)
     private fun help(command: Command) = Result.Help(command)
-    private fun failure(command: Command, exception: RuntimeError) = Result.Failure(command, exception)
+    private fun failure(command: Command, exception: RunError) = Result.Failure(command, exception)
 
     private var index = 0
     private val current: String
diff --git a/src/commonMain/kotlin/com/infendro/cli/command/help/DefaultHelpRenderer.kt b/src/commonMain/kotlin/com/infendro/cli/command/help/DefaultHelpRenderer.kt
index 36bed08..76e4b5b 100644
--- a/src/commonMain/kotlin/com/infendro/cli/command/help/DefaultHelpRenderer.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/command/help/DefaultHelpRenderer.kt
@@ -75,7 +75,11 @@ object DefaultHelpRenderer : HelpRenderer {
     private fun StringBuilder.commands(commands: List<Command>) {
         appendLine("Commands:")
         for (command in commands) {
-            appendLine("  * ${command.name}")
+            val name = when {
+                command is Command.Fallback<*> -> "<${command.name}>"
+                else -> command.name
+            }
+            appendLine("  * $name")
         }
     }
 
diff --git a/src/commonMain/kotlin/com/infendro/cli/command/option/Option.kt b/src/commonMain/kotlin/com/infendro/cli/command/option/Option.kt
index ac3711a..5191848 100644
--- a/src/commonMain/kotlin/com/infendro/cli/command/option/Option.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/command/option/Option.kt
@@ -1,8 +1,10 @@
 package com.infendro.cli.command.option
 
-import com.infendro.cli.exception.build.InvalidRange
-import com.infendro.cli.exception.build.MissingOptionName
+import com.infendro.cli.error.build.InvalidOption
+import com.infendro.cli.error.build.InvalidRange
+import com.infendro.cli.error.build.MissingOptionName
 import com.infendro.cli.parser.Parser
+import com.infendro.cli.util.Regex.OPTION
 
 sealed class Option<T : Any>(
     val parser: Parser<T>,
@@ -33,6 +35,7 @@ sealed class Option<T : Any>(
     init {
         when {
             names.isEmpty() -> throw MissingOptionName()
+            names.any { !it.matches(OPTION) } -> throw InvalidOption(name)
             min !in 0..count || max == 0 -> throw InvalidRange()
         }
     }
diff --git a/src/commonMain/kotlin/com/infendro/cli/command/option/OptionFactory.kt b/src/commonMain/kotlin/com/infendro/cli/command/option/OptionFactory.kt
index 82ceaab..95924bf 100644
--- a/src/commonMain/kotlin/com/infendro/cli/command/option/OptionFactory.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/command/option/OptionFactory.kt
@@ -8,7 +8,7 @@ object OptionFactory {
     fun long(vararg names: String) = option(LongParser, *names)
     fun float(vararg names: String) = option(FloatParser, *names)
     fun double(vararg names: String) = option(DoubleParser, *names)
-    fun boolean(vararg names: String) = option(BooleanParser, true, *names)
+    fun boolean(vararg names: String) = option(BooleanParser, fallback = true, *names)
 
     inline fun <reified T : Enum<T>> enum(vararg names: String) = option(enumParser<T>(), *names)
 }
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/BuildException.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/BuildException.kt
new file mode 100644
index 0000000..ecefba9
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/BuildException.kt
@@ -0,0 +1,3 @@
+package com.infendro.cli.error.build
+
+abstract class BuildException : Error()
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateCommand.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateCommand.kt
new file mode 100644
index 0000000..354ce41
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateCommand.kt
@@ -0,0 +1,8 @@
+package com.infendro.cli.error.build
+
+class DuplicateCommand(
+    val command: String,
+) : BuildException() {
+    override val message: String
+        get() = """duplicate command "$command""""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateExecute.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateExecute.kt
new file mode 100644
index 0000000..f52c38d
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateExecute.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class DuplicateExecute : BuildException() {
+    override val message: String
+        get() = """duplicate execute block"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateOption.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateOption.kt
new file mode 100644
index 0000000..adf89a2
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateOption.kt
@@ -0,0 +1,8 @@
+package com.infendro.cli.error.build
+
+class DuplicateOption(
+    val name: String,
+) : BuildException() {
+    override val message: String
+        get() = """duplicate option "$name""""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateRenderer.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateRenderer.kt
new file mode 100644
index 0000000..347b803
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/DuplicateRenderer.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class DuplicateRenderer : BuildException() {
+    override val message: String
+        get() = """duplicate renderer"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidArgument.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidArgument.kt
new file mode 100644
index 0000000..6d7ae74
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidArgument.kt
@@ -0,0 +1,8 @@
+package com.infendro.cli.error.build
+
+class InvalidArgument(
+    val name: String,
+) : BuildException() {
+    override val message: String
+        get() = """invalid argument name "$name""""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidArgumentOrder.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidArgumentOrder.kt
new file mode 100644
index 0000000..f5b4b52
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidArgumentOrder.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class InvalidArgumentOrder : BuildException() {
+    override val message: String
+        get() = """invalid argument order"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidCommand.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidCommand.kt
new file mode 100644
index 0000000..a6d3a3a
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidCommand.kt
@@ -0,0 +1,8 @@
+package com.infendro.cli.error.build
+
+class InvalidCommand(
+    val name: String,
+) : BuildException() {
+    override val message: String
+        get() = """invalid command name "$name""""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidCommandOrder.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidCommandOrder.kt
new file mode 100644
index 0000000..eb65123
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidCommandOrder.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class InvalidCommandOrder : BuildException() {
+    override val message: String
+        get() = """invalid command order"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidFallback.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidFallback.kt
new file mode 100644
index 0000000..ac0c01a
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidFallback.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class InvalidFallback : BuildException() {
+    override val message: String
+        get() = """invalid fallback"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidOption.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidOption.kt
new file mode 100644
index 0000000..896d5df
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidOption.kt
@@ -0,0 +1,8 @@
+package com.infendro.cli.error.build
+
+class InvalidOption(
+    val name: String,
+) : BuildException() {
+    override val message: String
+        get() = """invalid option name "$name""""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidRange.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidRange.kt
new file mode 100644
index 0000000..f95e8df
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/InvalidRange.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class InvalidRange : BuildException() {
+    override val message: String
+        get() = """invalid range"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/build/MissingOptionName.kt b/src/commonMain/kotlin/com/infendro/cli/error/build/MissingOptionName.kt
new file mode 100644
index 0000000..a7997fd
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/build/MissingOptionName.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.build
+
+class MissingOptionName : BuildException() {
+    override val message: String
+        get() = """missing option name"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidArgumentCount.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/InvalidArgumentCount.kt
similarity index 90%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidArgumentCount.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/InvalidArgumentCount.kt
index 661b4c6..eee6b47 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidArgumentCount.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/InvalidArgumentCount.kt
@@ -1,11 +1,11 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 import com.infendro.cli.command.argument.Argument
 
 class InvalidArgumentCount(
     val argument: Argument<*>,
     val count: Int,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() {
             val expected = when {
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidOptionCount.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/InvalidOptionCount.kt
similarity index 89%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidOptionCount.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/InvalidOptionCount.kt
index 8be30ba..7d85c92 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidOptionCount.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/InvalidOptionCount.kt
@@ -1,11 +1,11 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 import com.infendro.cli.command.option.Option
 
 class InvalidOptionCount(
     val option: Option<*>,
     val count: Int,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() {
             val expected = when {
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidValue.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/InvalidValue.kt
similarity index 78%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidValue.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/InvalidValue.kt
index 40285a0..957308d 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/InvalidValue.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/InvalidValue.kt
@@ -1,11 +1,11 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 import kotlin.reflect.KClass
 
 class InvalidValue(
     val value: String,
     val type: KClass<*>,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() = """"$value" cannot be converted to ${type.simpleName ?: "Unknown"}"""
 }
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/MalformedOption.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/MalformedOption.kt
similarity index 68%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/MalformedOption.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/MalformedOption.kt
index b107348..bf3f09e 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/MalformedOption.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/MalformedOption.kt
@@ -1,8 +1,8 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 class MalformedOption(
     val option: String,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() = """malformed option "$option""""
 }
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/MissingOptionValue.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/MissingOptionValue.kt
similarity index 77%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/MissingOptionValue.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/MissingOptionValue.kt
index e7f6bb9..3e66f4b 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/MissingOptionValue.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/MissingOptionValue.kt
@@ -1,10 +1,10 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 import com.infendro.cli.command.option.Option
 
 class MissingOptionValue(
     val option: Option<*>,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() = """no value provided for option "${option.name}""""
 }
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/run/RunError.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/RunError.kt
new file mode 100644
index 0000000..b273109
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/RunError.kt
@@ -0,0 +1,5 @@
+package com.infendro.cli.error.run
+
+abstract class RunError {
+    abstract val message: String
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/error/run/UnexpectedArgument.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/UnexpectedArgument.kt
new file mode 100644
index 0000000..ab04ef7
--- /dev/null
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/UnexpectedArgument.kt
@@ -0,0 +1,6 @@
+package com.infendro.cli.error.run
+
+class UnexpectedArgument : RunError() {
+    override val message: String
+        get() = """unexpected argument"""
+}
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/UnknownCommand.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/UnknownCommand.kt
similarity index 68%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/UnknownCommand.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/UnknownCommand.kt
index 2474927..69903c4 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/UnknownCommand.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/UnknownCommand.kt
@@ -1,8 +1,8 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 class UnknownCommand(
     val command: String,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() = """unknown command "$command""""
 }
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/UnknownOption.kt b/src/commonMain/kotlin/com/infendro/cli/error/run/UnknownOption.kt
similarity index 68%
rename from src/commonMain/kotlin/com/infendro/cli/exception/run/UnknownOption.kt
rename to src/commonMain/kotlin/com/infendro/cli/error/run/UnknownOption.kt
index ce27c2b..1ccee98 100644
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/UnknownOption.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/error/run/UnknownOption.kt
@@ -1,8 +1,8 @@
-package com.infendro.cli.exception.run
+package com.infendro.cli.error.run
 
 class UnknownOption(
     val option: String,
-) : RuntimeError() {
+) : RunError() {
     override val message: String
         get() = """unknown option "$option""""
 }
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/CliException.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/CliException.kt
deleted file mode 100644
index 1f666d7..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/CliException.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-abstract class CliException : Exception()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateCommand.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateCommand.kt
deleted file mode 100644
index fbddcd7..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateCommand.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.infendro.cli.exception.build
-
-class DuplicateCommand(
-    val command: String,
-) : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateExecute.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateExecute.kt
deleted file mode 100644
index 818a437..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateExecute.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-class DuplicateExecute : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateOption.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateOption.kt
deleted file mode 100644
index 687e9ea..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/DuplicateOption.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.infendro.cli.exception.build
-
-class DuplicateOption(
-    val name: String,
-) : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidArgument.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidArgument.kt
deleted file mode 100644
index ad901b4..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidArgument.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidArgument(
-    val name: String,
-) : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidArgumentOrder.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidArgumentOrder.kt
deleted file mode 100644
index 6e2a498..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidArgumentOrder.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidArgumentOrder : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidCommand.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidCommand.kt
deleted file mode 100644
index f49aacd..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidCommand.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidCommand(
-    val name: String,
-) : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidCommandOrder.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidCommandOrder.kt
deleted file mode 100644
index 4c35cf4..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidCommandOrder.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidCommandOrder : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidFallback.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidFallback.kt
deleted file mode 100644
index cc50110..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidFallback.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidFallback : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidOption.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidOption.kt
deleted file mode 100644
index f336e4d..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidOption.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidOption(
-    val name: String,
-) : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidRange.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidRange.kt
deleted file mode 100644
index 23eec23..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/InvalidRange.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-class InvalidRange : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/build/MissingOptionName.kt b/src/commonMain/kotlin/com/infendro/cli/exception/build/MissingOptionName.kt
deleted file mode 100644
index 8725a87..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/build/MissingOptionName.kt
+++ /dev/null
@@ -1,3 +0,0 @@
-package com.infendro.cli.exception.build
-
-class MissingOptionName : CliException()
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/RuntimeError.kt b/src/commonMain/kotlin/com/infendro/cli/exception/run/RuntimeError.kt
deleted file mode 100644
index d53e4c2..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/RuntimeError.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.infendro.cli.exception.run
-
-abstract class RuntimeError {
-    abstract val message: String
-}
diff --git a/src/commonMain/kotlin/com/infendro/cli/exception/run/UnexpectedArgument.kt b/src/commonMain/kotlin/com/infendro/cli/exception/run/UnexpectedArgument.kt
deleted file mode 100644
index 8570525..0000000
--- a/src/commonMain/kotlin/com/infendro/cli/exception/run/UnexpectedArgument.kt
+++ /dev/null
@@ -1,6 +0,0 @@
-package com.infendro.cli.exception.run
-
-class UnexpectedArgument : RuntimeError() {
-    override val message: String
-        get() = """unexpected argument"""
-}
diff --git a/src/commonMain/kotlin/com/infendro/cli/parser/Parser.kt b/src/commonMain/kotlin/com/infendro/cli/parser/Parser.kt
index d2bfe1b..4541b0d 100644
--- a/src/commonMain/kotlin/com/infendro/cli/parser/Parser.kt
+++ b/src/commonMain/kotlin/com/infendro/cli/parser/Parser.kt
@@ -1,7 +1,7 @@
 package com.infendro.cli.parser
 
-import com.infendro.cli.exception.run.InvalidValue
-import com.infendro.cli.exception.run.RuntimeError
+import com.infendro.cli.error.run.InvalidValue
+import com.infendro.cli.error.run.RunError
 import kotlin.reflect.KClass
 
 abstract class Parser<T : Any>(
@@ -13,7 +13,7 @@ abstract class Parser<T : Any>(
         ) : Result<T>()
 
         data class Failure<T : Any>(
-            val error: RuntimeError,
+            val error: RunError,
         ) : Result<T>()
     }