diff --git a/src/Composer/Json/JsonFile.php b/src/Composer/Json/JsonFile.php
index fd43c9148..7594b85cc 100644
--- a/src/Composer/Json/JsonFile.php
+++ b/src/Composer/Json/JsonFile.php
@@ -206,7 +206,7 @@ class JsonFile
                     $msg .= ', extra comma';
                 } elseif (preg_match('#((?<=[^\\\\])\\\\(?!["\\\\/bfnrt]|u[a-f0-9]{4}))#i', $json, $match, PREG_OFFSET_CAPTURE)) {
                     $msg .= ', unescaped backslash (\\)';
-                } elseif (preg_match('#(["}\]]) *\r?\n *"#', $json, $match, PREG_OFFSET_CAPTURE)) {
+                } elseif (preg_match('#(["}\]])(?: *\r?\n *)+"#', $json, $match, PREG_OFFSET_CAPTURE)) {
                     $msg .= ', missing comma';
                     $charOffset = 1;
                 } elseif (preg_match('#^ *([a-z0-9_-]+) *:#mi', $json, $match, PREG_OFFSET_CAPTURE)) {
@@ -215,6 +215,8 @@ class JsonFile
                     $msg .= ', use double quotes (") instead of single quotes (\')';
                 } elseif (preg_match('#(\[".*?":.*?\])#', $json, $match, PREG_OFFSET_CAPTURE)) {
                     $msg .= ', you must use the hash syntax (e.g. {"foo": "bar"}) instead of array syntax (e.g. ["foo", "bar"])';
+                } elseif (preg_match('#".*?"( *["{\[])#', $json, $match, PREG_OFFSET_CAPTURE)) {
+                    $msg .= ', missing colon';
                 }
                 if (isset($match[1][1])) {
                     $preError = substr($json, 0, $match[1][1]);
diff --git a/tests/Composer/Test/Json/JsonFileTest.php b/tests/Composer/Test/Json/JsonFileTest.php
index 231839416..4ebf7b0c5 100644
--- a/tests/Composer/Test/Json/JsonFileTest.php
+++ b/tests/Composer/Test/Json/JsonFileTest.php
@@ -84,6 +84,25 @@ class JsonFileTest extends \PHPUnit_Framework_TestCase
         $this->expectParseException('missing comma on line 2, char 21', $json);
     }
 
+    public function testParseErrorDetectMissingCommaMultiline()
+    {
+        $json = '{
+        "foo": "barbar"
+
+        "bar": "foo"
+}';
+        $this->expectParseException('missing comma on line 2, char 24', $json);
+    }
+
+    public function testParseErrorDetectMissingColon()
+    {
+        $json = '{
+        "foo": "bar",
+        "bar" "foo"
+}';
+        $this->expectParseException('missing colon on line 3, char 14', $json);
+    }
+
     public function testSimpleJsonString()
     {
         $data = array('name' => 'composer/composer');