diff --git a/lib/src/ast/selector/list.dart b/lib/src/ast/selector/list.dart
index 2c3167fb..ce7495ee 100644
--- a/lib/src/ast/selector/list.dart
+++ b/lib/src/ast/selector/list.dart
@@ -32,8 +32,8 @@ class SelectorList extends Selector {
   SassList get asSassList {
     return new SassList(components.map((complex) {
       return new SassList(
-          complex.components
-              .map((component) => new SassString(component.toString())),
+          complex.components.map((component) =>
+              new SassString(component.toString(), quotes: false)),
           ListSeparator.space);
     }), ListSeparator.comma);
   }
diff --git a/lib/src/functions.dart b/lib/src/functions.dart
index 3a1c27bb..e6c228ea 100644
--- a/lib/src/functions.dart
+++ b/lib/src/functions.dart
@@ -108,7 +108,8 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
         if (first is SassColor) {
           return new SassString(
               "rgba(${first.red}, ${first.green}, ${first.blue}, "
-              "${arguments[1].toCssString()})");
+              "${arguments[1].toCssString()})",
+              quotes: false);
         } else {
           return _functionString('rgba', arguments);
         }
@@ -116,7 +117,8 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
         var color = arguments[0].assertColor("color");
         return new SassString(
             "rgba(${color.red}, ${color.green}, ${color.blue}, "
-            "${arguments[1].toCssString()})");
+            "${arguments[1].toCssString()})",
+            quotes: false);
       }
 
       var color = arguments[0].assertColor("color");
@@ -277,7 +279,7 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
   new BuiltInCallable.overloaded("saturate", {
     r"$number": (arguments) {
       var number = arguments[0].assertNumber("number");
-      return new SassString("saturate(${number.toCssString()})");
+      return new SassString("saturate(${number.toCssString()})", quotes: false);
     },
     r"$color, $amount": (arguments) {
       var color = arguments[0].assertColor("color");
@@ -536,7 +538,8 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
         component.toRadixString(16).padLeft(2, '0').toUpperCase();
     return new SassString(
         "#${hexString(fuzzyRound(color.alpha * 255))}${hexString(color.red)}"
-        "${hexString(color.green)}${hexString(color.blue)}");
+        "${hexString(color.green)}${hexString(color.blue)}",
+        quotes: false);
   }),
 
   // ## Strings
@@ -544,7 +547,7 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
   new BuiltInCallable("unquote", r"$string", (arguments) {
     var string = arguments[0].assertString("string");
     if (!string.hasQuotes) return string;
-    return new SassString(string.text);
+    return new SassString(string.text, quotes: false);
   }),
 
   new BuiltInCallable("quote", r"$string", (arguments) {
@@ -789,8 +792,8 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
       "list-separator",
       r"$list",
       (arguments) => arguments[0].separator == ListSeparator.comma
-          ? new SassString("comma")
-          : new SassString("space")),
+          ? new SassString("comma", quotes: false)
+          : new SassString("space", quotes: false)),
 
   new BuiltInCallable("is-bracketed", r"$list",
       (arguments) => new SassBoolean(arguments[0].hasBrackets)),
@@ -841,7 +844,7 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
     var argumentList = arguments[0];
     if (argumentList is SassArgumentList) {
       return new SassMap(mapMap(argumentList.keywords,
-          key: (String key, Value _) => new SassString(key)));
+          key: (String key, Value _) => new SassString(key, quotes: false)));
     } else {
       throw new SassScriptException(
           "\$args: $argumentList is not an argument list.");
@@ -927,7 +930,8 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
     var selector = arguments[0].assertCompoundSelector(name: "selector");
 
     return new SassList(
-        selector.components.map((simple) => new SassString(simple.toString())),
+        selector.components
+            .map((simple) => new SassString(simple.toString(), quotes: false)),
         ListSeparator.comma);
   }),
 
@@ -942,20 +946,21 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
   }),
 
   new BuiltInCallable("inspect", r"$value",
-      (arguments) => new SassString(arguments.first.toString())),
+      (arguments) => new SassString(arguments.first.toString(), quotes: false)),
 
   new BuiltInCallable("type-of", r"$value", (arguments) {
     var value = arguments[0];
-    if (value is SassArgumentList) return new SassString("arglist");
-    if (value is SassBoolean) return new SassString("bool");
-    if (value is SassColor) return new SassString("color");
-    if (value is SassList) return new SassString("list");
-    if (value is SassMap) return new SassString("map");
-    if (value is SassNull) return new SassString("null");
-    if (value is SassNumber) return new SassString("number");
-    if (value is SassFunction) return new SassString("function");
+    if (value is SassArgumentList)
+      return new SassString("arglist", quotes: false);
+    if (value is SassBoolean) return new SassString("bool", quotes: false);
+    if (value is SassColor) return new SassString("color", quotes: false);
+    if (value is SassList) return new SassString("list", quotes: false);
+    if (value is SassMap) return new SassString("map", quotes: false);
+    if (value is SassNull) return new SassString("null", quotes: false);
+    if (value is SassNumber) return new SassString("number", quotes: false);
+    if (value is SassFunction) return new SassString("function", quotes: false);
     assert(value is SassString);
-    return new SassString("string");
+    return new SassString("string", quotes: false);
   }),
 
   new BuiltInCallable("unit", r"$number", (arguments) {
@@ -988,16 +993,19 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
     _uniqueID += _random.nextInt(36) + 1;
     if (_uniqueID > math.pow(36, 6)) _uniqueID %= math.pow(36, 6) as int;
     // The leading "u" ensures that the result is a valid identifier.
-    return new SassString("u${_uniqueID.toRadixString(36).padLeft(6, '0')}");
+    return new SassString("u${_uniqueID.toRadixString(36).padLeft(6, '0')}",
+        quotes: false);
   })
 ]);
 
 /// Returns a string representation of [name] called with [arguments], as though
 /// it were a plain CSS function.
 SassString _functionString(String name, Iterable<Value> arguments) =>
-    new SassString("$name(" +
-        arguments.map((argument) => argument.toCssString()).join(', ') +
-        ")");
+    new SassString(
+        "$name(" +
+            arguments.map((argument) => argument.toCssString()).join(', ') +
+            ")",
+        quotes: false);
 
 /// Asserts that [number] is a percentage or has no units, and normalizes the
 /// value.
diff --git a/lib/src/node/value/string.dart b/lib/src/node/value/string.dart
index 3e199104..86b717a9 100644
--- a/lib/src/node/value/string.dart
+++ b/lib/src/node/value/string.dart
@@ -22,7 +22,7 @@ Object newNodeSassString(SassString value) =>
 /// The JS constructor for the `sass.types.String` class.
 final Function stringConstructor = createClass(
     (_NodeSassString thisArg, String value, [SassString dartValue]) {
-  thisArg.dartValue = dartValue ?? new SassString(value);
+  thisArg.dartValue = dartValue ?? new SassString(value, quotes: false);
 }, {
   'getValue': (_NodeSassString thisArg) => thisArg.dartValue.text,
   'setValue': (_NodeSassString thisArg, String value) {
diff --git a/lib/src/value.dart b/lib/src/value.dart
index 6df2101b..f1c975ba 100644
--- a/lib/src/value.dart
+++ b/lib/src/value.dart
@@ -226,7 +226,7 @@ abstract class Value implements ext.Value {
   /// **Note:** this function should not be called outside the `sass` package.
   /// It's not guaranteed to be stable across versions.
   Value singleEquals(Value other) =>
-      new SassString("${toCssString()}=${other.toCssString()}");
+      new SassString("${toCssString()}=${other.toCssString()}", quotes: false);
 
   /// The SassScript `>` operation.
   ///
@@ -279,7 +279,7 @@ abstract class Value implements ext.Value {
       return new SassString(toCssString() + other.text,
           quotes: other.hasQuotes);
     } else {
-      return new SassString(toCssString() + other.toCssString());
+      return new SassString(toCssString() + other.toCssString(), quotes: false);
     }
   }
 
@@ -288,32 +288,32 @@ abstract class Value implements ext.Value {
   /// **Note:** this function should not be called outside the `sass` package.
   /// It's not guaranteed to be stable across versions.
   Value minus(Value other) =>
-      new SassString("${toCssString()}-${other.toCssString()}");
+      new SassString("${toCssString()}-${other.toCssString()}", quotes: false);
 
   /// The SassScript `/` operation.
   ///
   /// **Note:** this function should not be called outside the `sass` package.
   /// It's not guaranteed to be stable across versions.
   Value dividedBy(Value other) =>
-      new SassString("${toCssString()}/${other.toCssString()}");
+      new SassString("${toCssString()}/${other.toCssString()}", quotes: false);
 
   /// The SassScript unary `+` operation.
   ///
   /// **Note:** this function should not be called outside the `sass` package.
   /// It's not guaranteed to be stable across versions.
-  Value unaryPlus() => new SassString("+${toCssString()}");
+  Value unaryPlus() => new SassString("+${toCssString()}", quotes: false);
 
   /// The SassScript unary `-` operation.
   ///
   /// **Note:** this function should not be called outside the `sass` package.
   /// It's not guaranteed to be stable across versions.
-  Value unaryMinus() => new SassString("-${toCssString()}");
+  Value unaryMinus() => new SassString("-${toCssString()}", quotes: false);
 
   /// The SassScript unary `/` operation.
   ///
   /// **Note:** this function should not be called outside the `sass` package.
   /// It's not guaranteed to be stable across versions.
-  Value unaryDivide() => new SassString("/${toCssString()}");
+  Value unaryDivide() => new SassString("/${toCssString()}", quotes: false);
 
   /// The SassScript unary `not` operation.
   ///
diff --git a/lib/src/visitor/async_evaluate.dart b/lib/src/visitor/async_evaluate.dart
index cf25e7e6..fa23453c 100644
--- a/lib/src/visitor/async_evaluate.dart
+++ b/lib/src/visitor/async_evaluate.dart
@@ -225,7 +225,8 @@ class _EvaluateVisitor
               ? null
               : new ValueExpression(
                   new SassMap(mapMap(args.keywords,
-                      key: (String key, Value _) => new SassString(key),
+                      key: (String key, Value _) =>
+                          new SassString(key, quotes: false),
                       value: (String _, Value value) => value)),
                   _callableSpan));
 
@@ -1343,7 +1344,7 @@ class _EvaluateVisitor
       }
       buffer.writeCharCode($rparen);
 
-      return new SassString(buffer.toString());
+      return new SassString(buffer.toString(), quotes: false);
     } else {
       return null;
     }
diff --git a/lib/src/visitor/evaluate.dart b/lib/src/visitor/evaluate.dart
index fc392b78..e309f506 100644
--- a/lib/src/visitor/evaluate.dart
+++ b/lib/src/visitor/evaluate.dart
@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/synchronize.dart for details.
 //
-// Checksum: d4ffc2a9cc2c3e8e202705c44e03c7acb7822356
+// Checksum: 0d20d8293daaad022a0a20115cc88b80704e2ad7
 
 import 'dart:math' as math;
 
@@ -227,7 +227,8 @@ class _EvaluateVisitor
               ? null
               : new ValueExpression(
                   new SassMap(mapMap(args.keywords,
-                      key: (String key, Value _) => new SassString(key),
+                      key: (String key, Value _) =>
+                          new SassString(key, quotes: false),
                       value: (String _, Value value) => value)),
                   _callableSpan));
 
@@ -1321,7 +1322,7 @@ class _EvaluateVisitor
       }
       buffer.writeCharCode($rparen);
 
-      return new SassString(buffer.toString());
+      return new SassString(buffer.toString(), quotes: false);
     } else {
       return null;
     }
diff --git a/test/dart_api/function_test.dart b/test/dart_api/function_test.dart
index ee9e691f..7a423eb3 100644
--- a/test/dart_api/function_test.dart
+++ b/test/dart_api/function_test.dart
@@ -29,7 +29,7 @@ main() {
       new Callable("foo", r"$arg", expectAsync1((arguments) {
         expect(arguments, hasLength(1));
         expect(arguments.first.assertString().text, equals("bar"));
-        return new SassString("result");
+        return new SassString("result", quotes: false);
       }))
     ]);
 
@@ -42,7 +42,7 @@ main() {
         expect(arguments, hasLength(1));
         expect(arguments.first.assertString().text, equals("bar"));
         await pumpEventQueue();
-        return new SassString("result");
+        return new SassString("result", quotes: false);
       }))
     ]);
 
diff --git a/test/dart_api/value/list_test.dart b/test/dart_api/value/list_test.dart
index a0451992..d6a1625f 100644
--- a/test/dart_api/value/list_test.dart
+++ b/test/dart_api/value/list_test.dart
@@ -26,40 +26,49 @@ main() {
     test("returns its contents as a list", () {
       expect(
           value.asList,
-          equals(
-              [new SassString("a"), new SassString("b"), new SassString("c")]));
+          equals([
+            new SassString("a", quotes: false),
+            new SassString("b", quotes: false),
+            new SassString("c", quotes: false)
+          ]));
     });
 
     test("equals the same list", () {
       expect(
           value,
-          equalsWithHash(new SassList(
-              [new SassString("a"), new SassString("b"), new SassString("c")],
-              ListSeparator.comma)));
+          equalsWithHash(new SassList([
+            new SassString("a", quotes: false),
+            new SassString("b", quotes: false),
+            new SassString("c", quotes: false)
+          ], ListSeparator.comma)));
     });
 
     test("doesn't equal a value with different metadata", () {
       expect(
           value,
-          isNot(equals(new SassList(
-              [new SassString("a"), new SassString("b"), new SassString("c")],
-              ListSeparator.space))));
+          isNot(equals(new SassList([
+            new SassString("a", quotes: false),
+            new SassString("b", quotes: false),
+            new SassString("c", quotes: false)
+          ], ListSeparator.space))));
 
       expect(
           value,
           isNot(equals(new SassList([
-            new SassString("a"),
-            new SassString("b"),
-            new SassString("c")
+            new SassString("a", quotes: false),
+            new SassString("b", quotes: false),
+            new SassString("c", quotes: false)
           ], ListSeparator.comma, brackets: true))));
     });
 
     test("doesn't equal a value with different contents", () {
       expect(
           value,
-          isNot(equals(new SassList(
-              [new SassString("a"), new SassString("x"), new SassString("c")],
-              ListSeparator.comma))));
+          isNot(equals(new SassList([
+            new SassString("a", quotes: false),
+            new SassString("x", quotes: false),
+            new SassString("c", quotes: false)
+          ], ListSeparator.comma))));
     });
 
     group("sassIndexToListIndex()", () {
@@ -76,7 +85,9 @@ main() {
       });
 
       test("rejects a non-number", () {
-        expect(() => value.sassIndexToListIndex(new SassString("foo")),
+        expect(
+            () => value
+                .sassIndexToListIndex(new SassString("foo", quotes: false)),
             throwsSassScriptException);
       });
 
@@ -233,15 +244,17 @@ main() {
 
   group("new SassList()", () {
     test("creates a list with the given contents and metadata", () {
-      var list = new SassList([new SassString("a")], ListSeparator.space);
-      expect(list.asList, equals([new SassString("a")]));
+      var list = new SassList(
+          [new SassString("a", quotes: false)], ListSeparator.space);
+      expect(list.asList, equals([new SassString("a", quotes: false)]));
       expect(list.separator, equals(ListSeparator.space));
       expect(list.hasBrackets, isFalse);
     });
 
     test("can create a bracketed list", () {
       expect(
-          new SassList([new SassString("a")], ListSeparator.space,
+          new SassList(
+                  [new SassString("a", quotes: false)], ListSeparator.space,
                   brackets: true)
               .hasBrackets,
           isTrue);
@@ -249,7 +262,8 @@ main() {
 
     test("can create a short list with an undecided separator", () {
       expect(
-          new SassList([new SassString("a")], ListSeparator.undecided)
+          new SassList(
+                  [new SassString("a", quotes: false)], ListSeparator.undecided)
               .separator,
           equals(ListSeparator.undecided));
       expect(new SassList([], ListSeparator.undecided).separator,
@@ -258,8 +272,10 @@ main() {
 
     test("can't create a long list with an undecided separator", () {
       expect(
-          () => new SassList([new SassString("a"), new SassString("b")],
-              ListSeparator.undecided),
+          () => new SassList([
+                new SassString("a", quotes: false),
+                new SassString("b", quotes: false)
+              ], ListSeparator.undecided),
           throwsArgumentError);
     });
   });
diff --git a/test/dart_api/value/map_test.dart b/test/dart_api/value/map_test.dart
index 4c0f2b4c..fe7febfe 100644
--- a/test/dart_api/value/map_test.dart
+++ b/test/dart_api/value/map_test.dart
@@ -23,8 +23,10 @@ main() {
       expect(
           value.contents,
           equals({
-            new SassString("a"): new SassString("b"),
-            new SassString("c"): new SassString("d")
+            new SassString("a", quotes: false):
+                new SassString("b", quotes: false),
+            new SassString("c", quotes: false):
+                new SassString("d", quotes: false)
           }));
     });
 
@@ -32,10 +34,14 @@ main() {
       expect(
           value.asList,
           equals([
-            new SassList([new SassString("a"), new SassString("b")],
-                ListSeparator.space),
-            new SassList(
-                [new SassString("c"), new SassString("d")], ListSeparator.space)
+            new SassList([
+              new SassString("a", quotes: false),
+              new SassString("b", quotes: false)
+            ], ListSeparator.space),
+            new SassList([
+              new SassString("c", quotes: false),
+              new SassString("d", quotes: false)
+            ], ListSeparator.space)
           ]));
     });
 
@@ -64,8 +70,10 @@ main() {
       expect(
           value,
           equalsWithHash(new SassMap({
-            new SassString("a"): new SassString("b"),
-            new SassString("c"): new SassString("d")
+            new SassString("a", quotes: false):
+                new SassString("b", quotes: false),
+            new SassString("c", quotes: false):
+                new SassString("d", quotes: false)
           })));
     });
 
@@ -73,10 +81,14 @@ main() {
       expect(
           value,
           isNot(equals(new SassList([
-            new SassList([new SassString("a"), new SassString("b")],
-                ListSeparator.space),
-            new SassList(
-                [new SassString("c"), new SassString("d")], ListSeparator.space)
+            new SassList([
+              new SassString("a", quotes: false),
+              new SassString("b", quotes: false)
+            ], ListSeparator.space),
+            new SassList([
+              new SassString("c", quotes: false),
+              new SassString("d", quotes: false)
+            ], ListSeparator.space)
           ], ListSeparator.comma))));
     });
 
@@ -85,8 +97,10 @@ main() {
         expect(
             value,
             isNot(equals(new SassMap({
-              new SassString("a"): new SassString("x"),
-              new SassString("c"): new SassString("d")
+              new SassString("a", quotes: false):
+                  new SassString("x", quotes: false),
+              new SassString("c", quotes: false):
+                  new SassString("d", quotes: false)
             }))));
       });
 
@@ -94,25 +108,32 @@ main() {
         expect(
             value,
             isNot(equals(new SassMap({
-              new SassString("a"): new SassString("b"),
-              new SassString("x"): new SassString("d")
+              new SassString("a", quotes: false):
+                  new SassString("b", quotes: false),
+              new SassString("x", quotes: false):
+                  new SassString("d", quotes: false)
             }))));
       });
 
       test("a missing pair", () {
         expect(
             value,
-            isNot(equals(
-                new SassMap({new SassString("a"): new SassString("b")}))));
+            isNot(equals(new SassMap({
+              new SassString("a", quotes: false):
+                  new SassString("b", quotes: false)
+            }))));
       });
 
       test("an additional pair", () {
         expect(
             value,
             isNot(equals(new SassMap({
-              new SassString("a"): new SassString("b"),
-              new SassString("c"): new SassString("d"),
-              new SassString("e"): new SassString("f")
+              new SassString("a", quotes: false):
+                  new SassString("b", quotes: false),
+              new SassString("c", quotes: false):
+                  new SassString("d", quotes: false),
+              new SassString("e", quotes: false):
+                  new SassString("f", quotes: false)
             }))));
       });
     });
@@ -165,7 +186,13 @@ main() {
   });
 
   test("new SassMap() creates a map with the given contents", () {
-    var list = new SassMap({new SassString("a"): new SassString("b")});
-    expect(list.contents, equals({new SassString("a"): new SassString("b")}));
+    var list = new SassMap({
+      new SassString("a", quotes: false): new SassString("b", quotes: false)
+    });
+    expect(
+        list.contents,
+        equals({
+          new SassString("a", quotes: false): new SassString("b", quotes: false)
+        }));
   });
 }
diff --git a/test/dart_api/value/string_test.dart b/test/dart_api/value/string_test.dart
index 7109c7e8..2b7eca9b 100644
--- a/test/dart_api/value/string_test.dart
+++ b/test/dart_api/value/string_test.dart
@@ -206,7 +206,7 @@ main() {
 
   group("new SassString.empty()", () {
     test("creates an empty unquoted string", () {
-      var string = new SassString.empty();
+      var string = new SassString.empty(quotes: false);
       expect(string.text, isEmpty);
       expect(string.hasQuotes, isFalse);
     });
@@ -220,7 +220,7 @@ main() {
 
   group("new SassString()", () {
     test("creates an unquoted string with the given text", () {
-      var string = new SassString("a b c");
+      var string = new SassString("a b c", quotes: false);
       expect(string.text, equals("a b c"));
       expect(string.hasQuotes, isFalse);
     });