diff --git a/src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java b/src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java
index d57939e67..6dcfab7bf 100644
--- a/src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java
+++ b/src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java
@@ -522,13 +522,13 @@ public <S> Void visit(SignedExpression signedExpression, S context) {
 
     @Override
     public <S> Void visit(IsNullExpression isNullExpression, S context) {
-
+        isNullExpression.getLeftExpression().accept(this, context);
         return null;
     }
 
     @Override
     public <S> Void visit(IsBooleanExpression isBooleanExpression, S context) {
-
+        isBooleanExpression.getLeftExpression().accept(this, context);
         return null;
     }