diff --git a/src/format/formulas.rs b/src/format/formulas.rs
index ac2b6f7..c577fd0 100644
--- a/src/format/formulas.rs
+++ b/src/format/formulas.rs
@@ -64,6 +64,7 @@ fn requires_parentheses<'formula>(formula: &'formula crate::Formula,
 			| Formula::Exists(_)
 			| Formula::ForAll(_)
 			| Formula::And(_)
+			| Formula::Or(_)
 			| Formula::Implies(_)
 				=> true,
 			_ => false,
@@ -1511,4 +1512,165 @@ mod tests
 				if_and_only_if(vec![and(p2q2r2())]), if_and_only_if(vec![and(p3q3r3())])])),
 			"p1 and q1 and r1 <-> p2 and q2 and r2 <-> p3 and q3 and r3");
 	}
+
+	#[test]
+	fn format_combination_or_and_lower()
+	{
+		// Or + or
+		assert_eq!(format(
+			or(vec![or(vec![p()]), or(vec![q()]), or(vec![r()])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![and(vec![or(vec![p()])]), and(vec![or(vec![q()])]), and(vec![or(vec![r()])])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![or(vec![or(vec![p()])]), or(vec![or(vec![q()])]),
+				or(vec![or(vec![r()])])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![or(vec![p()])]), if_and_only_if(vec![or(vec![q()])]),
+				if_and_only_if(vec![or(vec![r()])])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![or(p1q1r1()), or(p2q2r2()), or(p3q3r3())])),
+			"p1 or q1 or r1 or p2 or q2 or r2 or p3 or q3 or r3");
+		assert_eq!(format(
+			or(vec![and(vec![or(p1q1r1())]), and(vec![or(p2q2r2())]), and(vec![or(p3q3r3())])])),
+			"p1 or q1 or r1 or p2 or q2 or r2 or p3 or q3 or r3");
+		assert_eq!(format(
+			or(vec![or(vec![or(p1q1r1())]), or(vec![or(p2q2r2())]), or(vec![or(p3q3r3())])])),
+			"p1 or q1 or r1 or p2 or q2 or r2 or p3 or q3 or r3");
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![or(p1q1r1())]), if_and_only_if(vec![or(p2q2r2())]),
+				if_and_only_if(vec![or(p3q3r3())])])),
+			"p1 or q1 or r1 or p2 or q2 or r2 or p3 or q3 or r3");
+
+		// Or + implies
+		assert_eq!(format(
+			or(vec![implies_right(p1(), q1()), implies_right(p2(), q2()),
+				implies_right(p3(), q3())])),
+			"(p1 -> q1) or (p2 -> q2) or (p3 -> q3)");
+		assert_eq!(format(
+			or(vec![and(vec![implies_right(p1(), q1())]), and(vec![implies_right(p2(), q2())]),
+				and(vec![implies_right(p3(), q3())])])),
+			"(p1 -> q1) or (p2 -> q2) or (p3 -> q3)");
+		assert_eq!(format(
+			or(vec![or(vec![implies_right(p1(), q1())]), or(vec![implies_right(p2(), q2())]),
+				or(vec![implies_right(p3(), q3())])])),
+			"(p1 -> q1) or (p2 -> q2) or (p3 -> q3)");
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![implies_right(p1(), q1())]),
+				if_and_only_if(vec![implies_right(p2(), q2())]),
+				if_and_only_if(vec![implies_right(p3(), q3())])])),
+			"(p1 -> q1) or (p2 -> q2) or (p3 -> q3)");
+		assert_eq!(format(
+			or(vec![implies_left(p1(), q1()), implies_left(p2(), q2()),
+				implies_left(p3(), q3())])),
+			"(q1 <- p1) or (q2 <- p2) or (q3 <- p3)");
+		assert_eq!(format(
+			or(vec![and(vec![implies_left(p1(), q1())]), and(vec![implies_left(p2(), q2())]),
+				and(vec![implies_left(p3(), q3())])])),
+			"(q1 <- p1) or (q2 <- p2) or (q3 <- p3)");
+		assert_eq!(format(
+			or(vec![or(vec![implies_left(p1(), q1())]), or(vec![implies_left(p2(), q2())]),
+				or(vec![implies_left(p3(), q3())])])),
+			"(q1 <- p1) or (q2 <- p2) or (q3 <- p3)");
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![implies_left(p1(), q1())]),
+				if_and_only_if(vec![implies_left(p2(), q2())]),
+				if_and_only_if(vec![implies_left(p3(), q3())])])),
+			"(q1 <- p1) or (q2 <- p2) or (q3 <- p3)");
+		assert_eq!(format(
+			implies_right(or(p1q1r1()), or(p2q2r2()))),
+			"p1 or q1 or r1 -> p2 or q2 or r2");
+		assert_eq!(format(
+			implies_right(and(vec![or(p1q1r1())]), and(vec![or(p2q2r2())]))),
+			"p1 or q1 or r1 -> p2 or q2 or r2");
+		assert_eq!(format(
+			implies_right(or(vec![or(p1q1r1())]), or(vec![or(p2q2r2())]))),
+			"p1 or q1 or r1 -> p2 or q2 or r2");
+		assert_eq!(format(
+			implies_right(if_and_only_if(vec![or(p1q1r1())]),
+				if_and_only_if(vec![or(p2q2r2())]))),
+			"p1 or q1 or r1 -> p2 or q2 or r2");
+		assert_eq!(format(
+			implies_left(or(p1q1r1()), or(p2q2r2()))),
+			"p2 or q2 or r2 <- p1 or q1 or r1");
+		assert_eq!(format(
+			implies_left(and(vec![or(p1q1r1())]), and(vec![or(p2q2r2())]))),
+			"p2 or q2 or r2 <- p1 or q1 or r1");
+		assert_eq!(format(
+			implies_left(or(vec![or(p1q1r1())]), or(vec![or(p2q2r2())]))),
+			"p2 or q2 or r2 <- p1 or q1 or r1");
+		assert_eq!(format(
+			implies_left(if_and_only_if(vec![or(p1q1r1())]), if_and_only_if(vec![or(p2q2r2())]))),
+			"p2 or q2 or r2 <- p1 or q1 or r1");
+
+		// Or + if and only if
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![p()]), if_and_only_if(vec![q()]),
+				if_and_only_if(vec![r()])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![and(vec![if_and_only_if(vec![p()])]), and(vec![if_and_only_if(vec![q()])]),
+				and(vec![if_and_only_if(vec![r()])])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![or(vec![if_and_only_if(vec![p()])]), or(vec![if_and_only_if(vec![q()])]),
+				or(vec![if_and_only_if(vec![r()])])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![if_and_only_if(vec![p()])]),
+				if_and_only_if(vec![if_and_only_if(vec![q()])]),
+				if_and_only_if(vec![if_and_only_if(vec![r()])])])),
+			"p or q or r");
+		assert_eq!(format(
+			or(vec![if_and_only_if(p1q1r1()), if_and_only_if(p2q2r2()),
+				if_and_only_if(p3q3r3())])),
+			"(p1 <-> q1 <-> r1) or (p2 <-> q2 <-> r2) or (p3 <-> q3 <-> r3)");
+		assert_eq!(format(
+			or(vec![and(vec![if_and_only_if(p1q1r1())]), and(vec![if_and_only_if(p2q2r2())]),
+				and(vec![if_and_only_if(p3q3r3())])])),
+			"(p1 <-> q1 <-> r1) or (p2 <-> q2 <-> r2) or (p3 <-> q3 <-> r3)");
+		assert_eq!(format(
+			or(vec![or(vec![if_and_only_if(p1q1r1())]), or(vec![if_and_only_if(p2q2r2())]),
+				or(vec![if_and_only_if(p3q3r3())])])),
+			"(p1 <-> q1 <-> r1) or (p2 <-> q2 <-> r2) or (p3 <-> q3 <-> r3)");
+		assert_eq!(format(
+			or(vec![if_and_only_if(vec![if_and_only_if(p1q1r1())]),
+				if_and_only_if(vec![if_and_only_if(p2q2r2())]),
+				if_and_only_if(vec![if_and_only_if(p3q3r3())])])),
+			"(p1 <-> q1 <-> r1) or (p2 <-> q2 <-> r2) or (p3 <-> q3 <-> r3)");
+
+		assert_eq!(format(
+			if_and_only_if(vec![or(vec![p()]), or(vec![q()]), or(vec![r()])])),
+			"p <-> q <-> r");
+		assert_eq!(format(
+			if_and_only_if(vec![and(vec![or(vec![p()])]), and(vec![or(vec![q()])]),
+				and(vec![or(vec![r()])])])),
+			"p <-> q <-> r");
+		assert_eq!(format(
+			if_and_only_if(vec![or(vec![or(vec![p()])]), or(vec![or(vec![q()])]),
+				or(vec![or(vec![r()])])])),
+			"p <-> q <-> r");
+		assert_eq!(format(
+			if_and_only_if(vec![if_and_only_if(vec![or(vec![p()])]),
+				if_and_only_if(vec![or(vec![q()])]), if_and_only_if(vec![or(vec![r()])])])),
+			"p <-> q <-> r");
+		assert_eq!(format(
+			if_and_only_if(vec![or(p1q1r1()), or(p2q2r2()), or(p3q3r3())])),
+			"p1 or q1 or r1 <-> p2 or q2 or r2 <-> p3 or q3 or r3");
+		assert_eq!(format(
+			if_and_only_if(vec![and(vec![or(p1q1r1())]), and(vec![or(p2q2r2())]),
+				and(vec![or(p3q3r3())])])),
+			"p1 or q1 or r1 <-> p2 or q2 or r2 <-> p3 or q3 or r3");
+		assert_eq!(format(
+			if_and_only_if(vec![or(vec![or(p1q1r1())]), or(vec![or(p2q2r2())]),
+				or(vec![or(p3q3r3())])])),
+			"p1 or q1 or r1 <-> p2 or q2 or r2 <-> p3 or q3 or r3");
+		assert_eq!(format(
+			if_and_only_if(vec![if_and_only_if(vec![or(p1q1r1())]),
+				if_and_only_if(vec![or(p2q2r2())]), if_and_only_if(vec![or(p3q3r3())])])),
+			"p1 or q1 or r1 <-> p2 or q2 or r2 <-> p3 or q3 or r3");
+	}
 }