diff --git a/src/DateRange.php b/src/DateRange.php
index 849e6a4..cde58b7 100644
--- a/src/DateRange.php
+++ b/src/DateRange.php
@@ -263,4 +263,50 @@ public function equals($b)
         $b = static::wrap($b);
         return $this->from == $b->from && $this->to == $b->to;
     }
-}
\ No newline at end of file
+
+    /**
+     * @param array|self $a
+     * @param array|self $b
+     * @return int
+     */
+    public static function compare($a, $b)
+    {
+        $a = static::wrap($a);
+        $b = static::wrap($b);
+
+        $fromA = $a->getFrom();
+        $fromB = $b->getFrom();
+        $toA = $a->getTo();
+        $toB = $b->getTo();
+
+        // by from (NULL first)
+        if (!$fromA && $fromB) {
+            return -1;
+        } else if ($fromA && !$fromB) {
+            return 1;
+        } else if ($fromA && $fromB) {
+            // ASC by from
+            if ($fromA < $fromB) {
+                return -1;
+            } else if ($fromA > $fromB) {
+                return 1;
+            }
+        }
+
+        // by to (NULL last)
+        if (!$toA && $toB) {
+            return 1;
+        } else if ($toA && !$toB) {
+            return -1;
+        } else if ($toA && $toB) {
+            // ASC by to
+            if ($toA < $toB) {
+                return -1;
+            } else if ($toA > $toB) {
+                return 1;
+            }
+        }
+
+        return 0;
+    }
+}
diff --git a/src/DateRangeCollection.php b/src/DateRangeCollection.php
index afcffdc..29ef47e 100644
--- a/src/DateRangeCollection.php
+++ b/src/DateRangeCollection.php
@@ -20,40 +20,7 @@ public function __construct($collection)
         }
 
         usort($this->ranges, function (DateRange $a, DateRange $b) {
-            $fromA = $a->getFrom();
-            $fromB = $b->getFrom();
-            $toA = $a->getTo();
-            $toB = $b->getTo();
-
-            // by from (NULL first)
-            if (!$fromA && $fromB) {
-                return -1;
-            } else if ($fromA && !$fromB) {
-                return 1;
-            } else if ($fromA && $fromB) {
-                // ASC by from
-                if ($fromA < $fromB) {
-                    return -1;
-                } else if ($fromA > $fromB) {
-                    return 1;
-                }
-            }
-
-            // by to (NULL last)
-            if (!$toA && $toB) {
-                return 1;
-            } else if ($toA && !$toB) {
-                return -1;
-            } else if ($toA && $toB) {
-                // ASC by to
-                if ($toA < $toB) {
-                    return -1;
-                } else if ($toA > $toB) {
-                    return 1;
-                }
-            }
-
-            return 0;
+            return DateRange::compare($a, $b);
         });
     }
 
@@ -194,4 +161,4 @@ public function subtract($subtrahends)
 
         return new static($minuends);
     }
-}
\ No newline at end of file
+}