diff --git a/lib/waterline/utils/query/private/normalize-where-clause.js b/lib/waterline/utils/query/private/normalize-where-clause.js
index 2e96b981f..7520c1407 100644
--- a/lib/waterline/utils/query/private/normalize-where-clause.js
+++ b/lib/waterline/utils/query/private/normalize-where-clause.js
@@ -298,13 +298,10 @@ module.exports = function normalizeWhereClause(whereClause, modelIdentity, orm,
       // > here, we have to be more forgiving-- both for usability and backwards-compatibility.
 
 
-      //  ╔═╗╔╦╗╦═╗╦╔═╗  ╦╔═╔═╗╦ ╦╔═╗  ┬ ┬┬┌┬┐┬ ┬  ╦ ╦╔╗╔╔╦╗╔═╗╔═╗╦╔╗╔╔═╗╔╦╗  ┬─┐┬ ┬┌─┐
-      //  ╚═╗ ║ ╠╦╝║╠═╝  ╠╩╗║╣ ╚╦╝╚═╗  ││││ │ ├─┤  ║ ║║║║ ║║║╣ ╠╣ ║║║║║╣  ║║  ├┬┘├─┤└─┐
-      //  ╚═╝ ╩ ╩╚═╩╩    ╩ ╩╚═╝ ╩ ╚═╝  └┴┘┴ ┴ ┴ ┴  ╚═╝╝╚╝═╩╝╚═╝╚  ╩╝╚╝╚═╝═╩╝  ┴└─┴ ┴└─┘
-      // Strip out any keys with undefined values.
+      // Convert undefined keys to null
       _.each(_.keys(branch), function (key){
         if (_.isUndefined(branch[key])) {
-          delete branch[key];
+          throw flaverr('E_CONSTRAINT_WOULD_MATCH_NOTHING', new Error(`Unexpected undefined value in WHERE clause for column: ${key}`));
         }
       });