diff --git a/src/core/guillotine.scala b/src/core/guillotine-core.scala
similarity index 98%
rename from src/core/guillotine.scala
rename to src/core/guillotine-core.scala
index 3647226..e845ce2 100644
--- a/src/core/guillotine.scala
+++ b/src/core/guillotine-core.scala
@@ -225,7 +225,7 @@ object Command:
     val commandText: Text = formattedArguments(command.arguments)
     if commandText.contains(t"\"") then t"sh\"\"\"$commandText\"\"\"" else t"sh\"$commandText\""
 
-  given Show[Command] = command => formattedArguments(command.arguments)
+  given Command is Showable = command => formattedArguments(command.arguments)
 
 case class Command(arguments: Text*) extends Executable:
   def fork[ResultType]()(using working: WorkingDirectory)
@@ -244,7 +244,7 @@ object Pipeline:
     pipeline => msg"${pipeline.commands.map(_.show).join(t" | ")}"
 
   given Debug[Pipeline] = _.commands.map(_.debug).join(t" | ")
-  given Show[Pipeline] = _.commands.map(_.show).join(t" | ")
+  given Pipeline is Showable = _.commands.map(_.show).join(t" | ")
 
 case class Pipeline(commands: Command*) extends Executable:
   def fork[ResultType]()(using working: WorkingDirectory)
@@ -381,7 +381,6 @@ trait Parameterizable:
   def show(value: Self): Text
 
 object Guillotine:
-
   def sh(context: Expr[StringContext], parts: Expr[Seq[Any]])(using Quotes): Expr[Command] =
     import quotes.reflect.*
 
@@ -393,3 +392,6 @@ object Guillotine:
         '{${Sh.Prefix.expand(context, parts)}.asInstanceOf[commandType]}
 
 given Realm = realm"guillotine"
+
+extension (inline context: StringContext)
+  transparent inline def sh(inline parts: Any*): Any = ${Guillotine.sh('context, 'parts)}
diff --git a/src/core/posix.scala b/src/core/guillotine.PosixCommands.scala
similarity index 100%
rename from src/core/posix.scala
rename to src/core/guillotine.PosixCommands.scala
diff --git a/src/core/shextension.scala b/src/core/shextension.scala
deleted file mode 100644
index 2cc4073..0000000
--- a/src/core/shextension.scala
+++ /dev/null
@@ -1,22 +0,0 @@
-/*
-    Guillotine, version [unreleased]. Copyright 2024 Jon Pretty, Propensive OÜ.
-
-    The primary distribution site is: https://propensive.com/
-
-    Licensed under the Apache License, Version 2.0 (the "License"); you may not use this
-    file except in compliance with the License. You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software distributed under the
-    License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
-    either express or implied. See the License for the specific language governing permissions
-    and limitations under the License.
-*/
-
-package guillotine
-
-import language.experimental.captureChecking
-
-extension (inline context: StringContext)
-  transparent inline def sh(inline parts: Any*): Any = ${Guillotine.sh('context, 'parts)}