diff --git a/include/sqlpp11/is_not_null.h b/include/sqlpp11/is_not_null.h
index 4fd3706f..f5f232ac 100644
--- a/include/sqlpp11/is_not_null.h
+++ b/include/sqlpp11/is_not_null.h
@@ -52,7 +52,7 @@ namespace sqlpp
   struct is_not_null_t : public expression_operators<is_not_null_t<Operand>, boolean>,
                          public alias_operators<is_not_null_t<Operand>>
   {
-    using _traits = make_traits<boolean, tag::is_expression, tag::is_selectable>;
+    using _traits = make_traits<boolean, tag::is_expression, tag::is_selectable, tag::requires_parens>;
     using _nodes = detail::type_vector<Operand>;
 
     using _auto_alias_t = is_not_null_alias_t;
@@ -73,9 +73,8 @@ namespace sqlpp
   template <typename Context, typename Operand>
   Context& serialize(const is_not_null_t<Operand>& t, Context& context)
   {
-    context << "(";
     serialize_operand(t._operand, context);
-    context << " IS NOT NULL)";
+    context << " IS NOT NULL";
     return context;
   }
 }  // namespace sqlpp
diff --git a/include/sqlpp11/is_null.h b/include/sqlpp11/is_null.h
index 8baa6a59..1c692b1a 100644
--- a/include/sqlpp11/is_null.h
+++ b/include/sqlpp11/is_null.h
@@ -52,7 +52,7 @@ namespace sqlpp
   struct is_null_t : public expression_operators<is_null_t<Operand>, boolean>,
                      public alias_operators<is_null_t<Operand>>
   {
-    using _traits = make_traits<boolean, tag::is_expression, tag::is_selectable>;
+    using _traits = make_traits<boolean, tag::is_expression, tag::is_selectable, tag::requires_parens>;
     using _nodes = detail::type_vector<Operand>;
 
     using _auto_alias_t = is_null_alias_t;
@@ -73,9 +73,8 @@ namespace sqlpp
   template <typename Context, typename Operand>
   Context& serialize(const is_null_t<Operand>& t, Context& context)
   {
-    context << "(";
     serialize_operand(t._operand, context);
-    context << " IS NULL)";
+    context << " IS NULL";
     return context;
   }
 }  // namespace sqlpp
diff --git a/tests/core/serialize/CMakeLists.txt b/tests/core/serialize/CMakeLists.txt
index 8ee4c4ee..6032f1a4 100644
--- a/tests/core/serialize/CMakeLists.txt
+++ b/tests/core/serialize/CMakeLists.txt
@@ -33,6 +33,8 @@ set(test_files
     From.cpp
     In.cpp
     Insert.cpp
+    IsNotNull.cpp
+    IsNull.cpp
     Lower.cpp
     Max.cpp
     Min.cpp
diff --git a/tests/core/serialize/IsNotNull.cpp b/tests/core/serialize/IsNotNull.cpp
new file mode 100644
index 00000000..a880b3fe
--- /dev/null
+++ b/tests/core/serialize/IsNotNull.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2023, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Sample.h"
+#include "compare.h"
+#include <sqlpp11/sqlpp11.h>
+
+int IsNotNull(int, char* [])
+{
+  const auto bar = test::TabBar{};
+
+  // Single column.
+  compare(__LINE__, is_not_null(bar.beta), "tab_bar.beta IS NOT NULL");
+
+  // Expression.
+  compare(__LINE__, is_not_null(bar.beta + "suffix"), "(tab_bar.beta||'suffix') IS NOT NULL");
+
+  // With sub select.
+  compare(__LINE__, is_not_null(select(sqlpp::value("something").as(sqlpp::alias::a))), "(SELECT 'something' AS a) IS NOT NULL");
+
+  // Requires parens.
+  compare(__LINE__, is_not_null(bar.beta) or bar.beta == "", "((tab_bar.beta IS NOT NULL) OR (tab_bar.beta=''))");
+  compare(__LINE__, bar.beta == "" or is_not_null(bar.beta), "((tab_bar.beta='') OR (tab_bar.beta IS NOT NULL))");
+
+  return 0;
+}
diff --git a/tests/core/serialize/IsNull.cpp b/tests/core/serialize/IsNull.cpp
new file mode 100644
index 00000000..ffadb530
--- /dev/null
+++ b/tests/core/serialize/IsNull.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2023, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Sample.h"
+#include "compare.h"
+#include <sqlpp11/sqlpp11.h>
+
+int IsNull(int, char* [])
+{
+  const auto bar = test::TabBar{};
+
+  // Single column.
+  compare(__LINE__, is_null(bar.beta), "tab_bar.beta IS NULL");
+
+  // Expression.
+  compare(__LINE__, is_null(bar.beta + "suffix"), "(tab_bar.beta||'suffix') IS NULL");
+
+  // With sub select.
+  compare(__LINE__, is_null(select(sqlpp::value("something").as(sqlpp::alias::a))), "(SELECT 'something' AS a) IS NULL");
+
+  // Requires parens.
+  compare(__LINE__, is_null(bar.beta) or bar.beta == "", "((tab_bar.beta IS NULL) OR (tab_bar.beta=''))");
+  compare(__LINE__, bar.beta == "" or is_null(bar.beta), "((tab_bar.beta='') OR (tab_bar.beta IS NULL))");
+
+  return 0;
+}
diff --git a/tests/core/serialize/Where.cpp b/tests/core/serialize/Where.cpp
index cbb1a7fe..99a2e7d1 100644
--- a/tests/core/serialize/Where.cpp
+++ b/tests/core/serialize/Where.cpp
@@ -63,11 +63,11 @@ int Where(int, char*[])
   // Sometimes
   compare(__LINE__, where(bar.gamma), " WHERE tab_bar.gamma");
   compare(__LINE__, where(bar.gamma == false), " WHERE (tab_bar.gamma=" + getFalse() + ")");
-  compare(__LINE__, where(bar.beta.is_null()), " WHERE (tab_bar.beta IS NULL)");
+  compare(__LINE__, where(bar.beta.is_null()), " WHERE tab_bar.beta IS NULL");
   compare(__LINE__, where(bar.beta == "SQL"), " WHERE (tab_bar.beta='SQL')");
   compare(__LINE__, where(is_equal_to_or_null(bar.beta, ::sqlpp::value_or_null("SQL"))), " WHERE (tab_bar.beta='SQL')");
   compare(__LINE__, where(is_equal_to_or_null(bar.beta, ::sqlpp::value_or_null<sqlpp::text>(::sqlpp::null))),
-          " WHERE (tab_bar.beta IS NULL)");
+          " WHERE tab_bar.beta IS NULL");
 #if __cplusplus >= 201703L
   // string_view argument
   std::string_view sqlString = "SQL";