diff --git a/src/command/command_builder.rs b/src/command/command_builder.rs
index b7e88be..6b409bb 100644
--- a/src/command/command_builder.rs
+++ b/src/command/command_builder.rs
@@ -1,3 +1,4 @@
+use super::builtin::Builtin;
 use super::unix_program::UnixProgram;
 use super::Command;
 
@@ -15,8 +16,15 @@ impl CommandBuilder {
         self
     }
 
-    pub fn build(&self) -> impl Command {
-        let command = UnixProgram::new(&self.argv);
+    pub fn build(&self) -> Box<dyn Command> {
+        let builtin = Builtin::new(&self.argv);
+        let command: Box<dyn Command>;
+
+        if builtin.is_err() {
+            command = Box::from(UnixProgram::new(&self.argv));
+        } else {
+            command = Box::from(builtin.unwrap());
+        }
 
         command
     }
diff --git a/src/command/command_sequence.rs b/src/command/command_sequence.rs
index 443d7c9..df61e36 100644
--- a/src/command/command_sequence.rs
+++ b/src/command/command_sequence.rs
@@ -7,14 +7,14 @@ pub struct CommandSequence {
 }
 
 impl CommandSequence {
-    pub fn new(command: impl Command + 'static) -> Self {
+    pub fn new(command: Box<dyn Command>) -> Self {
         Self {
-            command: Box::new(command),
+            command,
             next_command: None,
         }
     }
 
-    pub fn add(&mut self, command: impl Command + 'static) {
+    pub fn add(&mut self, command: Box<dyn Command>) {
         if self.next_command.is_none() {
             self.next_command = Some(Box::new(Self::new(command)));
         } else {
diff --git a/src/command/mod.rs b/src/command/mod.rs
index c369d2a..da38895 100644
--- a/src/command/mod.rs
+++ b/src/command/mod.rs
@@ -1,3 +1,4 @@
+pub mod builtin;
 pub mod command_builder;
 pub mod command_sequence;
 pub mod unix_program;