diff --git a/res/composer-schema.json b/res/composer-schema.json
index 22e527428..10058a347 100644
--- a/res/composer-schema.json
+++ b/res/composer-schema.json
@@ -77,32 +77,44 @@
         "require": {
             "type": "object",
             "description": "This is a hash of package name (keys) and version constraints (values) that are required to run this package.",
-            "additionalProperties": true
+            "additionalProperties": {
+                "type": "string"
+            }
         },
         "replace": {
             "type": "object",
             "description": "This is a hash of package name (keys) and version constraints (values) that can be replaced by this package.",
-            "additionalProperties": true
+            "additionalProperties": {
+                "type": "string"
+            }
         },
         "conflict": {
             "type": "object",
             "description": "This is a hash of package name (keys) and version constraints (values) that conflict with this package.",
-            "additionalProperties": true
+            "additionalProperties": {
+                "type": "string"
+            }
         },
         "provide": {
             "type": "object",
             "description": "This is a hash of package name (keys) and version constraints (values) that this package provides in addition to this package's name.",
-            "additionalProperties": true
+            "additionalProperties": {
+                "type": "string"
+            }
         },
         "require-dev": {
             "type": "object",
             "description": "This is a hash of package name (keys) and version constraints (values) that this package requires for developing it (testing tools and such).",
-            "additionalProperties": true
+            "additionalProperties": {
+                "type": "string"
+            }
         },
         "suggest": {
             "type": "object",
             "description": "This is a hash of package name (keys) and descriptions (values) that this package suggests work well with it (this will be suggested to the user during installation).",
-            "additionalProperties": true
+            "additionalProperties": {
+                "type": "string"
+            }
         },
         "config": {
             "type": "object",
@@ -134,12 +146,16 @@
                 "github-oauth": {
                     "type": "object",
                     "description": "A hash of domain name => github API oauth tokens, typically {\"github.com\":\"<token>\"}.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": "string"
+                    }
                 },
                 "gitlab-oauth": {
                     "type": "object",
                     "description": "A hash of domain name => gitlab API oauth tokens, typically {\"gitlab.com\":\"<token>\"}.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": "string"
+                    }
                 },
                 "disable-tls": {
                     "type": "boolean",
@@ -160,7 +176,20 @@
                 "http-basic": {
                     "type": "object",
                     "description": "A hash of domain name => {\"username\": \"...\", \"password\": \"...\"}.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": "object",
+                        "required": ["username", "password"],
+                        "properties": {
+                            "username": {
+                                "type": "string",
+                                "description": "The username used for HTTP Basic authentication"
+                            },
+                            "password": {
+                                "type": "string",
+                                "description": "The password used for HTTP Basic authentication"
+                            }
+                        }
+                    }
                 },
                 "store-auths": {
                     "type": ["string", "boolean"],
@@ -169,7 +198,9 @@
                 "platform": {
                     "type": "object",
                     "description": "This is a hash of package name (keys) and version (values) that will be used to mock the platform packages on this machine.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": "string"
+                    }
                 },
                 "vendor-dir": {
                     "type": "string",
@@ -275,12 +306,22 @@
                 "psr-0": {
                     "type": "object",
                     "description": "This is a hash of namespaces (keys) and the directories they can be found in (values, can be arrays of paths) by the autoloader.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": ["string", "array"],
+                        "items": {
+                            "type": "string"
+                        }
+                    }
                 },
                 "psr-4": {
                     "type": "object",
                     "description": "This is a hash of namespaces (keys) and the PSR-4 directories they can map to (values, can be arrays of paths) by the autoloader.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": ["string", "array"],
+                        "items": {
+                            "type": "string"
+                        }
+                    }
                 },
                 "classmap": {
                     "type": "array",
@@ -303,12 +344,22 @@
                 "psr-0": {
                     "type": "object",
                     "description": "This is a hash of namespaces (keys) and the directories they can be found into (values, can be arrays of paths) by the autoloader.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": ["string", "array"],
+                        "items": {
+                            "type": "string"
+                        }
+                    }
                 },
                 "psr-4": {
                     "type": "object",
                     "description": "This is a hash of namespaces (keys) and the PSR-4 directories they can map to (values, can be arrays of paths) by the autoloader.",
-                    "additionalProperties": true
+                    "additionalProperties": {
+                        "type": ["string", "array"],
+                        "items": {
+                            "type": "string"
+                        }
+                    }
                 },
                 "classmap": {
                     "type": "array",
diff --git a/tests/Composer/Test/Json/ComposerSchemaTest.php b/tests/Composer/Test/Json/ComposerSchemaTest.php
index b58eebccc..d4f63513a 100644
--- a/tests/Composer/Test/Json/ComposerSchemaTest.php
+++ b/tests/Composer/Test/Json/ComposerSchemaTest.php
@@ -44,6 +44,14 @@ class ComposerSchemaTest extends \PHPUnit_Framework_TestCase
         $this->assertTrue($this->check($json));
     }
 
+    public function testRequireTypes()
+    {
+        $json = '{"name": "name", "description": "description", "require": {"a": ["b"]} }';
+        $this->assertEquals(array(
+            array('property' => 'require.a', 'message' => 'Array value found, but a string is required', 'constraint' => 'type'),
+        ), $this->check($json));
+    }
+
     public function testMinimumStabilityValues()
     {
         $json = '{ "name": "vendor/package", "description": "generic description", "minimum-stability": "" }';