diff --git a/libraries.api.php b/libraries.api.php
index 66fa772..bfb0838 100644
--- a/libraries.api.php
+++ b/libraries.api.php
@@ -118,9 +118,12 @@
  *     - $variant: If the $library array belongs to a certain variant (see
  *       above), a string containing the variant name. NULL, otherwise.
  *     Valid callback groups are:
- *     - prepare: Callbacks registered in this group are applied as soon as the
+ *     - info: Callbacks registered in this group are applied as soon as the
  *       library information has been retrieved via hook_libraries_info() or
  *       info files.
+ *     - prepare: Callbacks registered in this group are applied when a library
+ *       is about to be detected, after the library path has been detected and
+ *       before the version callback is invoked.
  *     - detect: Callbacks registered in this group are applied as soon as
  *       library detection has been completed. At this point the library
  *       contains the version-specific information, if specified, and following
diff --git a/libraries.module b/libraries.module
index 9abbcad..e6fe393 100644
--- a/libraries.module
+++ b/libraries.module
@@ -262,6 +262,7 @@ function libraries_info($name = NULL) {
         'callbacks' => array(),
       );
       $properties['callbacks'] += array(
+        'info' => array(),
         'prepare' => array(),
         'detect' => array(),
         'load' => array(),
@@ -271,9 +272,9 @@ function libraries_info($name = NULL) {
     // Allow modules to alter the registered libraries.
     drupal_alter('libraries_info', $libraries);
 
-    // Invoke callbacks in the 'prepare' group.
+    // Invoke callbacks in the 'info' group.
     foreach ($libraries as &$properties) {
-      libraries_invoke('prepare', $properties);
+      libraries_invoke('info', $properties);
     }
   }
 
@@ -331,6 +332,9 @@ function libraries_detect($name) {
     return $library;
   }
 
+  // Invoke callbacks in the 'prepare' group.
+  libraries_invoke('prepare', $library);
+
   // Detect library version, if not hardcoded.
   if (!isset($library['version'])) {
     // We support both a single parameter, which is an associative array, and an