diff --git a/src/dat/controllers/factory.js b/src/dat/controllers/factory.js
index 897b267..0c10548 100644
--- a/src/dat/controllers/factory.js
+++ b/src/dat/controllers/factory.js
@@ -37,12 +37,18 @@ define([
 
           if (common.isNumber(arguments[2]) && common.isNumber(arguments[3])) {
 
-            // Has min and max.
-            return new NumberControllerSlider(object, property, arguments[2], arguments[3]);
+        	// Has min and max.
+            if (common.isNumber(arguments[4])) // has step
+              return new NumberControllerSlider(object, property, arguments[2], arguments[3], arguments[4]);
+            else
+              return new NumberControllerSlider(object, property, arguments[2], arguments[3]);
 
           } else {
 
-            return new NumberControllerBox(object, property, { min: arguments[2], max: arguments[3] });
+        	if (common.isNumber(arguments[4]))
+              return new NumberControllerBox(object, property, { min: arguments[2], max: arguments[3], step: arguments[4] });
+          	else
+              return new NumberControllerBox(object, property, { min: arguments[2], max: arguments[3] });
 
           }