diff --git a/lib/loader.js b/lib/loader.js
index 58fa5223..ca856cd3 100644
--- a/lib/loader.js
+++ b/lib/loader.js
@@ -21,7 +21,7 @@ module.exports = function(content, map) {
 
 	if(sourceMap) {
 		if (map) {
-			if (typeof map !== "string") {
+			if (typeof map === "string") {
 				map = JSON.stringify(map);
 			}
 
diff --git a/lib/processCss.js b/lib/processCss.js
index 585d37d0..5468fc79 100644
--- a/lib/processCss.js
+++ b/lib/processCss.js
@@ -48,7 +48,7 @@ var parserPlugin = postcss.plugin("css-loader-parser", function(options) {
 					url = url.url;
 				} else if(url.type === "string") {
 					url = url.value;
-				} else throw rule.error("Unexpected format" + rule.params);
+				} else throw rule.error("Unexpected format " + rule.params);
 				if (!url.replace(/\s/g, '').length) {
 					return;
 				}
diff --git a/test/sourceMapTest.js b/test/sourceMapTest.js
index c1c407d0..faf7578c 100644
--- a/test/sourceMapTest.js
+++ b/test/sourceMapTest.js
@@ -10,7 +10,7 @@ describe("source maps", function() {
 	testWithMap("falsy: undefined map doesn't cause an error", ".class { a: b c d; }", undefined, [
 		[1, ".class { a: b c d; }", ""]
 	]);
-	testWithMap("should don't generate sourceMap when `sourceMap: false` and map exist",
+	testWithMap("should don't generate sourceMap when `sourceMap: false` and map exists",
 		".class { a: b c d; }",
 		{
 			file: 'test.css',
@@ -28,7 +28,7 @@ describe("source maps", function() {
 			sourceMap: false
 		}
 	);
-	testWithMap("should don't generate sourceMap when `sourceMap: true` and map exist",
+	testWithMap("should don't generate sourceMap when `sourceMap: true` and map exists",
 		".class { a: b c d; }",
 		{
 			file: 'test.css',
@@ -54,6 +54,32 @@ describe("source maps", function() {
 			sourceMap: true
 		}
 	);
+    testWithMap("should don't generate sourceMap when `sourceMap: true` and map exists and string",
+        ".class { a: b c d; }",
+        JSON.stringify({
+            file: 'test.css',
+            mappings: 'AAAA,SAAS,SAAS,EAAE',
+            names: [],
+            sourceRoot: '',
+            sources: [ '/folder/test.css' ],
+            sourcesContent: [ '.class { a: b c d; }' ],
+            version: 3
+        }),
+        [
+            [1, ".class { a: b c d; }", "", {
+                file: 'test.css',
+                mappings: 'AAAA,SAAS,SAAS,EAAE',
+                names: [],
+                sourceRoot: '',
+                sources: [ '/folder/test.css' ],
+                sourcesContent: [ '.class { a: b c d; }' ],
+                version: 3
+            }]
+        ],
+        {
+            sourceMap: true
+        }
+    );
 	testMap("generate sourceMap (1 loader)", ".class { a: b c d; }", undefined, {
 		loaders: [{request: "/path/css-loader"}],
 		resource: "/folder/test.css",