diff --git a/lib/tasks/build-sass.js b/lib/tasks/build-sass.js
index 2f257913..b3a8b6a8 100644
--- a/lib/tasks/build-sass.js
+++ b/lib/tasks/build-sass.js
@@ -16,8 +16,8 @@ module.exports = function buildSass(config) {
 	const cwd = config.cwd || process.cwd();
 	const src = config.sass ? Promise.resolve(config.sass) : files.getMainSassPath(cwd);
 
-	return src.then(code => {
-		if (code) {
+	return src.then(sassFile => {
+		if (sassFile) {
 			const destFolder = config.buildFolder || files.getBuildFolderPath(cwd);
 			const dest = config.buildCss || 'main.css';
 
@@ -40,32 +40,34 @@ module.exports = function buildSass(config) {
 				grid: true
 			};
 
-			return readFile(code, 'utf-8')
-				.then(sassFile => {
+			let sassConfig;
+
+			if (!config.sassPrefix) {
+				sassConfig = { file: sassFile };
+			} else {
+				sassConfig = readFile(sassFile, 'utf-8').then(code => {
 					// Sass prefixing is used in our origami component specification sass tests
-					if (config.sassPrefix) {
-						sassFile = config.sassPrefix + sassFile;
-					}
+					return { data: config.sassPrefix + code };
+				});
+			}
 
+			return Promise.resolve(sassConfig)
+				.then(sassConfig => {
 					const includePaths = (config.sassIncludePaths || []).concat('bower_components').map(p => path.join(cwd, p));
 
 					// Ensure that the specified current working directory is included as the first path for node-sass to look into
 					includePaths.unshift(cwd);
 
-					const sassConfig = {
-						data: sassFile,
-						includePaths,
-						outputStyle: 'nested',
-
-						// This is an experimental LibSass feature. Use with caution.
-						// https://github.com/sass/node-sass#functions--v300---experimental
-						// We use this to silence the sass console output when running `obt test`.
-						// We also use this to hide warnings when building sass without the verbose flag.
-						functions: config.sassFunctions ? config.sassFunctions : {},
-					};
+					sassConfig.includePaths = includePaths;
+					sassConfig.outputStyle = 'nested';
+					// This is an experimental LibSass feature. Use with caution.
+					// https://github.com/sass/node-sass#functions--v300---experimental
+					// We use this to silence the sass console output when running `obt test`.
+					// We also use this to hide warnings when building sass without the verbose flag.
+					sassConfig.functions = config.sassFunctions ? config.sassFunctions : {};
 
 					if (useSourceMaps) {
-						sassConfig.sourceMap = code;
+						sassConfig.sourceMap = sassFile;
 						sassConfig.outFile = dest;
 
 						// Embeds the source map as a data URI
@@ -99,7 +101,7 @@ module.exports = function buildSass(config) {
 						.then(({ css }) => {
 							if (useSourceMaps) {
 								return postcss(postCssTransforms).process(css, {
-									from: code,
+									from: sassFile,
 									to: dest,
 									map: {
 										inline: true
diff --git a/test/integration/build/build.test.js b/test/integration/build/build.test.js
index b31d0a91..380c7dd2 100644
--- a/test/integration/build/build.test.js
+++ b/test/integration/build/build.test.js
@@ -525,7 +525,7 @@ describe('obt build', function () {
 .test__visual {
   -ms-grid-row: 1;
   grid-row: 1; }
-/*# sourceMappingURL=data:application/json;base64,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 */`);
+/*# sourceMappingURL=data:application/json;base64,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 */`);
 					});
 			});
 		});