diff --git a/src/lib.rs b/src/lib.rs
index 6c457ec..c772c5c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,7 @@
 #![feature(trait_alias)]
 
 pub mod error;
-pub(crate) mod output;
+pub mod output;
 pub mod translate;
 
 pub use error::Error;
diff --git a/src/main.rs b/src/main.rs
index 8bcb4d4..470c6ce 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,6 +10,10 @@ enum Command
 		/// ASP input program (one or multiple files)
 		#[structopt(parse(from_os_str), required(true))]
 		input: Vec<std::path::PathBuf>,
+
+		/// Output format (human-readable, tptp)
+		#[structopt(long, default_value = "human-readable")]
+		output_format: anthem::output::Format,
 	}
 }
 
@@ -21,7 +25,12 @@ fn main()
 
 	match command
 	{
-		Command::VerifyProgram{input} =>
+		Command::VerifyProgram
+		{
+			input,
+			output_format,
+		}
+			=>
 		{
 			if let Err(error) = anthem::translate::verify_properties::translate(&input)
 			{
diff --git a/src/output.rs b/src/output.rs
index 09538d1..640d2fd 100644
--- a/src/output.rs
+++ b/src/output.rs
@@ -1 +1,41 @@
 pub(crate) mod tptp;
+
+#[derive(Debug)]
+pub enum Format
+{
+	HumanReadable,
+	TPTP,
+}
+
+pub struct InvalidFormatError;
+
+impl std::fmt::Debug for InvalidFormatError
+{
+	fn fmt(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		write!(formatter, "invalid output format")
+	}
+}
+
+impl std::fmt::Display for InvalidFormatError
+{
+	fn fmt(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		write!(formatter, "{:?}", self)
+	}
+}
+
+impl std::str::FromStr for Format
+{
+	type Err = InvalidFormatError;
+
+	fn from_str(s: &str) -> Result<Self, Self::Err>
+	{
+		match s
+		{
+			"human-readable" => Ok(Format::HumanReadable),
+			"tptp" => Ok(Format::TPTP),
+			_ => Err(InvalidFormatError),
+		}
+	}
+}