diff --git a/lib/type/matrix/CcsFormat.js b/lib/type/matrix/CcsFormat.js
index 3571849ab..3339f25aa 100644
--- a/lib/type/matrix/CcsFormat.js
+++ b/lib/type/matrix/CcsFormat.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var util = require('../../util/index');
+var DimensionError = require('../../error/DimensionError');
 
 var array = util.array;
 var object = util.object;
diff --git a/lib/type/matrix/CrsFormat.js b/lib/type/matrix/CrsFormat.js
index 45fb31936..aa956f863 100644
--- a/lib/type/matrix/CrsFormat.js
+++ b/lib/type/matrix/CrsFormat.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var util = require('../../util/index');
+var DimensionError = require('../../error/DimensionError');
 
 var array = util.array,
     isNumber = util.number.isNumber,