diff --git a/lib/drivers/prototype.js b/lib/drivers/prototype.js
index 2e730c9..1e552fc 100644
--- a/lib/drivers/prototype.js
+++ b/lib/drivers/prototype.js
@@ -47,7 +47,7 @@ module.exports = {
           return (error = new RangeError('Condition for `'+key+'` cannot be undefined'))
 
         const op = cnd.operation || cnd.op || '='
-        if (cnd.value) cnd = cnd.value
+        if (cnd.value !== undefined) cnd = cnd.value
         return fmt('%s %s %s', field, op, escape(cnd))
       }