diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0238de9..77f66fa3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 1.5.1
+
+* Fix a bug where an absolute Windows path would be considered an `input:output`
+  pair.
+
 ## 1.5.0
 
 * Fix a bug where an importer would be passed an incorrectly-resolved URL when
diff --git a/lib/src/executable/options.dart b/lib/src/executable/options.dart
index 466232e8..3e42a643 100644
--- a/lib/src/executable/options.dart
+++ b/lib/src/executable/options.dart
@@ -3,10 +3,12 @@
 // https://opensource.org/licenses/MIT.
 
 import 'package:args/args.dart';
+import 'package:charcode/charcode.dart';
 import 'package:meta/meta.dart';
 
 import '../../sass.dart';
 import '../io.dart';
+import '../util/character.dart';
 import '../util/path.dart';
 
 /// The parsed and processed command-line options for the Sass executable.
@@ -180,12 +182,18 @@ class ExecutableOptions {
     var colonArgs = false;
     var positionalArgs = false;
     for (var argument in _options.rest) {
-      if (argument.isEmpty) {
-        _fail('Invalid argument "".');
-      } else if (argument.contains(":")) {
-        colonArgs = true;
-      } else {
+      if (argument.isEmpty) _fail('Invalid argument "".');
+
+      // If the colon appears at position 1, treat it as a Windows drive
+      // letter.
+      if (!argument.contains(":") ||
+          (_isWindowsPath(argument, 0) &&
+              // Look for colons after index 1, since that's where the drive
+              // letter is on Windows paths.
+              argument.indexOf(":", 2) == -1)) {
         positionalArgs = true;
+      } else {
+        colonArgs = true;
       }
     }
 
@@ -220,14 +228,26 @@ class ExecutableOptions {
     var seen = new Set<String>();
     var sourcesToDestinations = <String, String>{};
     for (var argument in _options.rest) {
-      var components = argument.split(":");
-      if (components.length > 2) {
-        _fail('"$argument" may only contain one ":".');
-      }
-      assert(components.length == 2);
+      String source;
+      String destination;
+      for (var i = 0; i < argument.length; i++) {
+        // A colon at position 1 may be a Windows drive letter and not a
+        // separator.
+        if (i == 1 && _isWindowsPath(argument, i - 1)) continue;
+
+        if (argument.codeUnitAt(i) == $colon) {
+          if (source == null) {
+            source = argument.substring(0, i);
+            destination = argument.substring(i + 1);
+          } else if (i != source.length + 2 ||
+              !_isWindowsPath(argument, i - 1)) {
+            // A colon 2 character after the separator may also be a Windows
+            // drive letter.
+            _fail('"$argument" may only contain one ":".');
+          }
+        }
+      }
 
-      var source = components.first;
-      var destination = components.last;
       if (!seen.add(source)) {
         _fail('Duplicate source "${source}".');
       }
@@ -246,6 +266,12 @@ class ExecutableOptions {
 
   Map<String, String> _sourcesToDestinations;
 
+  /// Returns whether [string] contains an absolute Windows path at [index].
+  bool _isWindowsPath(String string, int index) =>
+      string.length > index + 2 &&
+      isAlphabetic(string.codeUnitAt(index)) &&
+      string.codeUnitAt(index + 1) == $colon;
+
   /// Returns the sub-map of [sourcesToDestinations] for the given [source] and
   /// [destination] directories.
   Map<String, String> _listSourceDirectory(String source, String destination) {
diff --git a/lib/src/logger.dart b/lib/src/logger.dart
index 01c3d680..c8d2de41 100644
--- a/lib/src/logger.dart
+++ b/lib/src/logger.dart
@@ -6,7 +6,6 @@ import 'package:source_span/source_span.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import 'logger/stderr.dart';
-import 'util/path.dart';
 
 /// An interface for loggers that print messages produced by Sass stylesheets.
 ///
diff --git a/pubspec.yaml b/pubspec.yaml
index 2a6f3c41..b5c43193 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: sass
-version: 1.5.0
+version: 1.5.1
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass
diff --git a/test/cli/shared.dart b/test/cli/shared.dart
index 37e24dac..52fda601 100644
--- a/test/cli/shared.dart
+++ b/test/cli/shared.dart
@@ -8,6 +8,8 @@ import 'package:test/test.dart';
 import 'package:test_descriptor/test_descriptor.dart' as d;
 import 'package:test_process/test_process.dart';
 
+import 'package:sass/src/util/path.dart';
+
 /// Defines test that are shared between the Dart and Node.js CLI test suites.
 void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
   /// Runs the executable on [arguments] plus an output file, then verifies that
@@ -43,6 +45,22 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     await sass.shouldExit(0);
   });
 
+  // On Windows, this verifies that we don't consider the colon after a drive
+  // letter to be an `input:output` separator.
+  test("compiles an absolute Sass file to CSS", () async {
+    await d.file("test.scss", "a {b: 1 + 2}").create();
+
+    var sass = await runSass([p.absolute(p.join(d.sandbox, "test.scss"))]);
+    expect(
+        sass.stdout,
+        emitsInOrder([
+          "a {",
+          "  b: 3;",
+          "}",
+        ]));
+    await sass.shouldExit(0);
+  });
+
   test("writes a CSS file to disk", () async {
     await d.file("test.scss", "a {b: 1 + 2}").create();
 
diff --git a/test/cli/shared/colon_args.dart b/test/cli/shared/colon_args.dart
index af9c5b7e..7c2c9a48 100644
--- a/test/cli/shared/colon_args.dart
+++ b/test/cli/shared/colon_args.dart
@@ -8,6 +8,8 @@ import 'package:test/test.dart';
 import 'package:test_descriptor/test_descriptor.dart' as d;
 import 'package:test_process/test_process.dart';
 
+import 'package:sass/src/util/path.dart';
+
 /// Defines test that are shared between the Dart and Node.js CLI test suites.
 void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
   test("compiles multiple sources to multiple destinations", () async {
@@ -27,6 +29,20 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
         .validate();
   });
 
+  // On Windows, this verifies that we don't consider the colon after a drive
+  // letter to be an `input:output` separator.
+  test("compiles an absolute source to an absolute destination", () async {
+    await d.file("test.scss", "a {b: c}").create();
+
+    var input = p.absolute(p.join(d.sandbox, 'test.scss'));
+    var output = p.absolute(p.join(d.sandbox, 'out.css'));
+    var sass = await runSass(["--no-source-map", "$input:$output"]);
+    expect(sass.stdout, emitsDone);
+    await sass.shouldExit(0);
+
+    await d.file("out.css", equalsIgnoringWhitespace("a { b: c; }")).validate();
+  });
+
   test("creates destination directories", () async {
     await d.file("test.scss", "a {b: c}").create();