diff --git a/src/Contracts/Converter/CustomQueriesTrait.php b/src/Contracts/Converter/CustomQueriesTrait.php
index ef3e92e..9b97890 100644
--- a/src/Contracts/Converter/CustomQueriesTrait.php
+++ b/src/Contracts/Converter/CustomQueriesTrait.php
@@ -91,7 +91,7 @@ public function setCustomConditions(?string $query) : void
      */
     public function setCustomLimit(?int $limit): void
     {
-        if (is_null($limit)) {
+        if (!is_null($limit)) {
             $this->limit = $limit;
         }
     }
diff --git a/src/Converter/RequestUriToSql.php b/src/Converter/RequestUriToSql.php
index dfd7b46..398c823 100755
--- a/src/Converter/RequestUriToSql.php
+++ b/src/Converter/RequestUriToSql.php
@@ -367,7 +367,7 @@ protected function prepareNormalSql(array $searchCriteria, string $classname, st
                         $operator = 'LIKE';
                     }
 
-                    if ($value = 'null') {
+                    if ($value == 'null') {
                         $logicConector = !$vKey ? ' ' . $andOr . ' (' : ' OR ';
                         $sql .= $logicConector . $classname . '.' . $searchField . ' IS NULL';
                     } else {