diff --git a/README.md b/README.md
index 260c54a..e16ee92 100644
--- a/README.md
+++ b/README.md
@@ -54,18 +54,19 @@ When displaying the field on the front end, you can use the following single var
 
 This will either display a single category ID or a piped list if more than one category has been assigned (e.g. `1|3|17`).
 
-If you have enabled the 'Primary Category Assignment' option then you can access the various attributes of the primary category and the ID of it's parent (or itself if it has no parent) by appending the 'primary_category' modifier to the single field_name variable tag:
+If you have enabled the 'Primary Category Assignment' option then you can access the various attributes of the primary category and the ID of it's parent (or itself if it has no parent) by appending the 'primary' modifier to the single field_name variable tag:
 
-- `{field_name:primary_category:id}`
-- `{field_name:primary_category:parent_id}`
-- `{field_name:primary_category:name}`
-- `{field_name:primary_category:url_title}`
-- `{field_name:primary_category:description}`
-- `{field_name:primary_category:image}`
+- `{field_name:primary:category_id}`
+- `{field_name:primary:category_parent_id}`
+- `{field_name:primary:category_name}`
+- `{field_name:primary:category_url_title}`
+- `{field_name:primary:category_description}`
+- `{field_name:primary:category_image}`
+- `{field_name:primary:category_custom_field_name}`
 
 You can also return the primary category ID using the modifier with no attribute specified:
 
-- `{field_name:primary_category}`
+- `{field_name:primary}`
 
 ### Variable Pair
 
diff --git a/system/third_party/nf_categories_field/ft.nf_categories_field.php b/system/third_party/nf_categories_field/ft.nf_categories_field.php
index 3de4d14..9727b35 100644
--- a/system/third_party/nf_categories_field/ft.nf_categories_field.php
+++ b/system/third_party/nf_categories_field/ft.nf_categories_field.php
@@ -628,15 +628,8 @@ function replace_tag_catchall($data, $params = array(), $tagdata = FALSE, $modif
 
         switch($parts[0]) {
 
-            // If part 1 is {field_name:primary_category...
-            case 'primary_category':
-
-                $primary_category_id = FALSE;
-                $primary_category_parent_id = FALSE;
-                $primary_category_name = FALSE;
-                $primary_category_url_title = FALSE;
-                $primary_category_description = FALSE;
-                $primary_category_image = FALSE;
+            // If part 1 is {field_name:primary...
+            case 'primary':
 
                 // array_filter removes empty nodes, array_values re-indexes
                 $categories = array_values(array_filter(explode($settings['delimiter'], $data)));
@@ -645,7 +638,7 @@ function replace_tag_catchall($data, $params = array(), $tagdata = FALSE, $modif
 
                     $primary_category_id = ltrim($categories[0],'p');
 
-                    // If there is an attribute request {field_name:primary_category:something}
+                    // If there is an attribute request {field_name:primary:something}
                     if (isset($parts[1])) {
 
                         // Get extra category data
@@ -655,70 +648,54 @@ function replace_tag_catchall($data, $params = array(), $tagdata = FALSE, $modif
                             return FALSE;
                         } else {
 
-                            switch ($parts[1]) {
-
-                                // {field_name:primary_category:id}
-                                case 'id':
-                                    return $primary_category_id;
-                                    break;
-
-                                // {field_name:primary_category:name}
-                                case 'name':
-                                    $primary_category_name = $primary_category[0]['category_name'];
-                                    return $primary_category_name;
-                                    break;
-
-                                // {field_name:primary_category:url_title}
-                                case 'url_title':
-                                    $primary_category_url_title = $primary_category[0]['category_url_title'];
-                                    return $primary_category_url_title;
-                                    break;
-
-                                // {field_name:primary_category:description}
-                                case 'description':
-                                    $primary_category_description = $primary_category[0]['category_description'];
-                                    return $primary_category_description;
-                                    break;
-
-                                // {field_name:primary_category:image}
-                                case 'image':
-                                    $primary_category_image = $primary_category[0]['category_image'];
-                                    return $primary_category_image;
-                                    break;
-
-                                // {field_name:primary_category:parent_id}
-                                case 'parent_id':
-                                    // If there's a parent return it's ID, else return this categories ID
-                                    if ($primary_category[0]['category_parent_id']==0) {
-                                        $primary_category_parent_id = $primary_category[0]['category_id'];
-                                    } else {
-                                        $primary_category_parent_id = $primary_category[0]['category_parent_id'];
+                                if (array_key_exists($parts[1], $primary_category[0])) {
+
+                                    switch ($parts[1]) {
+
+                                        // {field_name:primary:category_id}
+                                        case 'id':
+                                            return $primary_category_id;
+                                            break;
+
+                                        // {field_name:primary:category_parent_id}
+                                        case 'parent_id':
+                                            // If there's a parent return it's ID, else return this categories ID
+                                            if ($primary_category[0]['category_parent_id']==0) {
+                                                $primary_category_parent_id = $primary_category[0]['category_id'];
+                                            } else {
+                                                $primary_category_parent_id = $primary_category[0]['category_parent_id'];
+                                            }
+                                            return $primary_category_parent_id;
+                                            break;
+
+                                        // {field_name:primary:category_ ... }
+                                        default:
+                                            // This includes custom category fields
+                                            return $primary_category[0][$parts[1]];
+
                                     }
-                                    return $primary_category_parent_id;
-                                    break;
 
-                            }
+                                } else {
+                                    return FALSE;
+                                }
 
                         }
 
                     // Just return the default without any attribute preference
                     } else {
 
-                        // {if {field_name:primary_category}} ...
-                        return TRUE;
+                        // {if {field_name:primary}} ...
+                        if ($categories AND substr( $categories[0], 0, 1 ) === "p") {
+                            return ltrim($categories[0],'p');
+                        } else {
+                            return FALSE;
+                        }
 
                     }
 
-                } else {
-                    return FALSE;
                 }
 
-                break;
-
-            default:
-                return FALSE;
-                break;
-
+            break;
         }
 
     }