diff --git a/lib/Drivers/DML/mongodb.js b/lib/Drivers/DML/mongodb.js
index 54d17fa6..14a10993 100644
--- a/lib/Drivers/DML/mongodb.js
+++ b/lib/Drivers/DML/mongodb.js
@@ -17,7 +17,7 @@ function Driver(config, connection, opts) {
 
 	this.opts.settings.set("properties.primary_key", "_id");
 	this.opts.settings.set("properties.association_key", function (name, field) {
-		return name + "_" + field.replace(/^_+/, '');
+		return name.toLowerCase() + "_" + field.replace(/^_+/, '');
 	});
 }
 
diff --git a/lib/Utilities.js b/lib/Utilities.js
index 41eee2df..e130dffb 100644
--- a/lib/Utilities.js
+++ b/lib/Utilities.js
@@ -163,7 +163,7 @@ exports.wrapFieldObject = function (obj, model, altName, alternatives) {
 		var assoc_key = model.settings.get("properties.association_key");
 
 		if (typeof assoc_key === "function") {
-		    obj = assoc_key(altName.toLowerCase(), model.id[0]);
+		    obj = assoc_key(altName, model.id[0]);
 		} else {
 			obj = assoc_key.replace("{name}", altName.toLowerCase())
 			               .replace("{field}", model.id[0]);
@@ -197,7 +197,7 @@ exports.formatField = function (model, name, required, reversed) {
 		if (reversed) {
 			field_name = keys[i];
 		} else if (typeof assoc_key === "function") {
-			field_name = assoc_key(name.toLowerCase(), keys[i]);
+			field_name = assoc_key(name, keys[i]);
 		} else {
 			field_name = assoc_key.replace("{name}", name.toLowerCase())
 			                      .replace("{field}", keys[i]);