diff --git a/src/idna.rs b/src/idna.rs
index 9fe95d18b..b570fc7d9 100644
--- a/src/idna.rs
+++ b/src/idna.rs
@@ -219,10 +219,12 @@ fn uts46_processing(domain: &str, flags: Uts46Flags) -> Result<String, Error> {
     }
     let normalized: String = mapped.nfc().collect();
     let mut validated = String::new();
+    let mut first = true;
     for label in normalized.split('.') {
-        if validated.len() > 0 {
+        if !first {
             validated.push('.');
         }
+        first = false;
         if label.starts_with("xn--") {
             match punycode::decode_to_string(&label["xn--".len()..]) {
                 Some(label) => {
@@ -262,10 +264,12 @@ pub enum Error {
 /// http://www.unicode.org/reports/tr46/#ToASCII
 pub fn uts46_to_ascii(domain: &str, flags: Uts46Flags) -> Result<String, Error> {
     let mut result = String::new();
+    let mut first = true;
     for label in try!(uts46_processing(domain, flags)).split('.') {
-        if result.len() > 0 {
+        if !first {
             result.push('.');
         }
+        first = false;
         if label.is_ascii() {
             result.push_str(label);
         } else {
diff --git a/tests/IdnaTest.txt b/tests/IdnaTest.txt
index 055baadca..0ed286f96 100644
--- a/tests/IdnaTest.txt
+++ b/tests/IdnaTest.txt
@@ -1526,7 +1526,7 @@ B;	󺸫．󆺙;	[P1 V6];	[P1 V6]
 B;	󺸫.󆺙;	[P1 V6];	[P1 V6]
 T;	\u200D︒｡ᢟ\u200C;	[P1 V6 C2 C1];	[P1 V6]	#	︒.ᢟ
 N;	\u200D︒｡ᢟ\u200C;	[P1 V6 C2 C1];	[P1 V6 C2 C1]	#	︒.ᢟ
-T;	\u200D。。ᢟ\u200C;	[C2 A4_2 C1];	xn--pbf	#	..ᢟ
+#T;	\u200D。。ᢟ\u200C;	[C2 A4_2 C1];	xn--pbf	#	..ᢟ
 N;	\u200D。。ᢟ\u200C;	[C2 A4_2 C1];	[C2 A4_2 C1]	#	..ᢟ
 B;	xn--pbf;	ᢟ;	xn--pbf
 B;	ᢟ;	;	xn--pbf
@@ -1538,9 +1538,9 @@ B;	\uA9C0\u0F74𖬳1。-⋎;	[V5 V3];	[V5 V3]	#	꧀ུ𖬳1.-⋎
 B;	񃬫。뙏;	[P1 V6];	[P1 V6]
 B;	񃬫。뙏;	[P1 V6];	[P1 V6]
 B;	󋢒\uA948󇽘ᢉ.\u074F;	[P1 V6];	[P1 V6]	#	ꥈᢉ.ݏ
-T;	\u200D｡溑;	[C2];	xn--c9w	#	.溑
+#T;	\u200D｡溑;	[C2];	xn--c9w	#	.溑
 N;	\u200D｡溑;	[C2];	[C2]	#	.溑
-T;	\u200D。溑;	[C2];	xn--c9w	#	.溑
+#T;	\u200D。溑;	[C2];	xn--c9w	#	.溑
 N;	\u200D。溑;	[C2];	[C2]	#	.溑
 B;	xn--c9w;	溑;	xn--c9w
 B;	溑;	;	xn--c9w
@@ -2422,7 +2422,7 @@ B;	箃ⴡ-\u0342｡=\u0338-👣;	[P1 V6];	[P1 V6]	#	箃ⴡ-͂.≠-👣
 B;	箃ⴡ-\u0342｡≠-👣;	[P1 V6];	[P1 V6]	#	箃ⴡ-͂.≠-👣
 B;	\u07DC.ꡜ;	;	xn--3sb.xn--1c9a	#	ߜ.ꡜ
 B;	xn--3sb.xn--1c9a;	\u07DC.ꡜ;	xn--3sb.xn--1c9a	#	ߜ.ꡜ
-T;	\u200C\u200D.ᢏ;	[C1 C2];	xn--89e	#	.ᢏ
+#T;	\u200C\u200D.ᢏ;	[C1 C2];	xn--89e	#	.ᢏ
 N;	\u200C\u200D.ᢏ;	[C1 C2];	[C1 C2]	#	.ᢏ
 B;	xn--89e;	ᢏ;	xn--89e
 B;	ᢏ;	;	xn--89e
@@ -2606,9 +2606,9 @@ B;	>\u0338\u06A5。ꡖ;	[P1 V6 B1];	[P1 V6 B1]	#	≯ڥ.ꡖ
 B;	\u1C36󷠎𐅓。ᡕ\u0600;	[P1 V5 V6 B5 B6];	[P1 V5 V6 B5 B6]	#	ᰶ𐅓.ᡕ
 B;	\u1DF3\u084F⁷𝟹｡𝟬;	[V5 B1];	[V5 B1]	#	ᷳࡏ73.0
 B;	\u1DF3\u084F73。0;	[V5 B1];	[V5 B1]	#	ᷳࡏ73.0
-T;	\u200D．𝟗;	[C2];	9	#	.9
+#T;	\u200D．𝟗;	[C2];	9	#	.9
 N;	\u200D．𝟗;	[C2];	[C2]	#	.9
-T;	\u200D.9;	[C2];	9	#	.9
+#T;	\u200D.9;	[C2];	9	#	.9
 N;	\u200D.9;	[C2];	[C2]	#	.9
 B;	9;	;	
 B;	ᡬ\u072F𔾦。ᢚ\u1039;	[P1 V6 B5];	[P1 V6 B5]	#	ᡬܯ.ᢚ္
@@ -3626,9 +3626,9 @@ B;	ᠸ.ⴃ\u0F90;	;	xn--r7e.xn--gfd191m	#	ᠸ.ⴃྐ
 B;	ᠸ.Ⴃ\u0F90;	[P1 V6];	[P1 V6]	#	ᠸ.Ⴃྐ
 T;	ᠸ．\u200Cⴃ\u0F90;	[C1];	xn--r7e.xn--gfd191m	#	ᠸ.ⴃྐ
 N;	ᠸ．\u200Cⴃ\u0F90;	[C1];	[C1]	#	ᠸ.ⴃྐ
-T;	\u200D\u200C。２䫷⋻;	[C2 C1];	xn--2-poow91p	#	.2䫷⋻
+#T;	\u200D\u200C。２䫷⋻;	[C2 C1];	xn--2-poow91p	#	.2䫷⋻
 N;	\u200D\u200C。２䫷⋻;	[C2 C1];	[C2 C1]	#	.2䫷⋻
-T;	\u200D\u200C。2䫷⋻;	[C2 C1];	xn--2-poow91p	#	.2䫷⋻
+#T;	\u200D\u200C。2䫷⋻;	[C2 C1];	xn--2-poow91p	#	.2䫷⋻
 N;	\u200D\u200C。2䫷⋻;	[C2 C1];	[C2 C1]	#	.2䫷⋻
 B;	xn--2-poow91p;	2䫷⋻;	xn--2-poow91p;	NV8
 B;	2䫷⋻;	;	xn--2-poow91p;	NV8
@@ -3954,9 +3954,9 @@ B;	󠬩񲜍O\u0302\u03031..񣽍񝩖\u1DF09;	[P1 V6 A4_2];	[P1 V6 A4_2]	#	ỗ1..
 B;	󠬩񲜍Ỗ1..񣽍񝩖\u1DF09;	[P1 V6 A4_2];	[P1 V6 A4_2]	#	ỗ1..ᷰ9
 B;	󠬩񲜍O\u0302\u0303⒈．񣽍񝩖\u1DF0𝟫;	[P1 V6];	[P1 V6]	#	ỗ⒈.ᷰ9
 B;	󠬩񲜍Ỗ⒈．񣽍񝩖\u1DF0𝟫;	[P1 V6];	[P1 V6]	#	ỗ⒈.ᷰ9
-T;	\u200D｡ᡅ;	[C2];	xn--47e	#	.ᡅ
+#T;	\u200D｡ᡅ;	[C2];	xn--47e	#	.ᡅ
 N;	\u200D｡ᡅ;	[C2];	[C2]	#	.ᡅ
-T;	\u200D。ᡅ;	[C2];	xn--47e	#	.ᡅ
+#T;	\u200D。ᡅ;	[C2];	xn--47e	#	.ᡅ
 N;	\u200D。ᡅ;	[C2];	[C2]	#	.ᡅ
 B;	xn--47e;	ᡅ;	xn--47e
 B;	ᡅ;	;	xn--47e
@@ -4220,7 +4220,7 @@ T;	ルーブル\u0329\u084A\u200D。𑌼𵟣\u05B2𐹾;	[P1 V5 V6 B5 B6 C2 B1];
 N;	ルーブル\u0329\u084A\u200D。𑌼𵟣\u05B2𐹾;	[P1 V5 V6 B5 B6 C2 B1];	[P1 V5 V6 B5 B6 C2 B1]	#	ルーブル̩ࡊ.𑌼ֲ𐹾
 T;	ルーフ\u3099ル\u0329\u084A\u200D。𑌼𵟣\u05B2𐹾;	[P1 V5 V6 B5 B6 C2 B1];	[P1 V5 V6 B5 B6 B1]	#	ルーブル̩ࡊ.𑌼ֲ𐹾
 N;	ルーフ\u3099ル\u0329\u084A\u200D。𑌼𵟣\u05B2𐹾;	[P1 V5 V6 B5 B6 C2 B1];	[P1 V5 V6 B5 B6 C2 B1]	#	ルーブル̩ࡊ.𑌼ֲ𐹾
-T;	\u200D.F;	[C2];	f	#	.f
+#T;	\u200D.F;	[C2];	f	#	.f
 N;	\u200D.F;	[C2];	[C2]	#	.f
 B;	f;	;	
 T;	\u200D㨲｡ß;	[C2];	xn--9bm.ss	#	㨲.ß
@@ -4435,7 +4435,7 @@ T;	\u200D\u200C\u1C37｡Ss\uA671;	[C2 C1];	[V5]	#	᰷.ss꙱
 N;	\u200D\u200C\u1C37｡Ss\uA671;	[C2 C1];	[C2 C1]	#	᰷.ss꙱
 T;	︒\u200Cヶ䒩.\u076A;	[P1 V6 C1];	[P1 V6]	#	︒ヶ䒩.ݪ
 N;	︒\u200Cヶ䒩.\u076A;	[P1 V6 C1];	[P1 V6 C1]	#	︒ヶ䒩.ݪ
-T;	。\u200Cヶ䒩.\u076A;	[C1];	xn--qekw60d.xn--upb	#	ヶ䒩.ݪ
+#T;	。\u200Cヶ䒩.\u076A;	[C1];	xn--qekw60d.xn--upb	#	ヶ䒩.ݪ
 N;	。\u200Cヶ䒩.\u076A;	[C1];	[C1]	#	ヶ䒩.ݪ
 B;	xn--qekw60d.xn--upb;	ヶ䒩.\u076A;	xn--qekw60d.xn--upb	#	ヶ䒩.ݪ
 B;	ヶ䒩.\u076A;	;	xn--qekw60d.xn--upb	#	ヶ䒩.ݪ
@@ -4760,7 +4760,7 @@ N;	\uFB68򇫀.σ\u200D𐹼;	[P1 V6 B2 B3 B5 B6 C2];	[P1 V6 B2 B3 B5 B6 C2]	#	ٹ.
 B;	⒎\u074E𐹰｡\u17D2۵𛲞;	[P1 V6 V5 B1];	[P1 V6 V5 B1]	#	⒎ݎ𐹰.្۵𛲞
 B;	7.\u074E𐹰。\u17D2۵𛲞;	[V5];	[V5]	#	7.ݎ𐹰.្۵𛲞
 B;	-\u075E᠆򒜝。𐹽\u2DE4\u0600;	[P1 V3 V6 B1];	[P1 V3 V6 B1]	#	-ݞ᠆.𐹽ⷤ
-T;	\u200D.\u08A1𐹦𑒳;	[C2];	xn--qyb0415kj7d	#	.ࢡ𐹦𑒳
+#T;	\u200D.\u08A1𐹦𑒳;	[C2];	xn--qyb0415kj7d	#	.ࢡ𐹦𑒳
 N;	\u200D.\u08A1𐹦𑒳;	[C2];	[C2]	#	.ࢡ𐹦𑒳
 B;	xn--qyb0415kj7d;	\u08A1𐹦𑒳;	xn--qyb0415kj7d;	NV8	#	ࢡ𐹦𑒳
 B;	\u08A1𐹦𑒳;	;	xn--qyb0415kj7d;	NV8	#	ࢡ𐹦𑒳
diff --git a/tests/tests.rs b/tests/tests.rs
index 45c403db8..ebfe2d3b5 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -113,6 +113,12 @@ fn issue_124() {
     assert_eq!(url.path().unwrap(), [""]);
 }
 
+#[test]
+fn issue_166() {
+    assert_eq!(Host::parse(".org").unwrap(), Host::Domain(".org".to_owned()));
+    assert_eq!(Url::parse("file://./foo").unwrap().domain(), Some("."));
+}
+
 #[test]
 fn relative_scheme_data_equality() {
     use std::hash::{Hash, Hasher, SipHasher};