diff --git a/src/format_tptp.rs b/src/format_tptp.rs
index 0d059a1..d4f4325 100644
--- a/src/format_tptp.rs
+++ b/src/format_tptp.rs
@@ -201,8 +201,8 @@ impl<'a> std::fmt::Debug for TermDisplay<'a>
 				foliage::Domain::Integer => write!(format, "N{}", declaration.name),
 			},
 			foliage::Term::Add(ref left, ref right) => write!(format, "$sum({:?}, {:?})", (&**left).display_tptp(), right.display_tptp()),
-			foliage::Term::Subtract(ref left, ref right) => write!(format, "$difference({:?} - {:?})", left.display_tptp(), right.display_tptp()),
-			foliage::Term::Multiply(ref left, ref right) => write!(format, "$product({:?} * {:?})", left.display_tptp(), right.display_tptp()),
+			foliage::Term::Subtract(ref left, ref right) => write!(format, "$difference({:?}, {:?})", left.display_tptp(), right.display_tptp()),
+			foliage::Term::Multiply(ref left, ref right) => write!(format, "$product({:?}, {:?})", left.display_tptp(), right.display_tptp()),
 			foliage::Term::Negative(ref argument) => write!(format, "$uminus({:?})", argument.display_tptp()),
 		}
 	}