diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1d0cd71..d0350a8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,16 @@
 # Changelog
 
+## Unreleased
+
+### Fixed
+
+- An OR condition written as `['is', value]` / `['is not', value]` (or handed
+  to `OrConditionSpecification` as `['is', column, value]`) was passed to
+  yiisoft/db verbatim and rendered `col IS 'value'` — a syntax error on MySQL
+  and PostgreSQL that SQLite alone accepts. The OR path now maps `is` / `is not`
+  to `=` / `!=` exactly as `visitComparison()` does: a `null` operand still
+  renders `IS NULL` / `IS NOT NULL`, any other operand a plain equality (#34).
+
 ## 1.3.0 — 2026-09-13
 
 ### Fixed
diff --git a/README.md b/README.md
index 5650928..662e997 100644
--- a/README.md
+++ b/README.md
@@ -285,9 +285,12 @@ Benchmarks live in `benchmarks/` and run via `composer bench` (requires
   (`'age' => ['>', 18]`, `'type' => ['in', ['a', 'b']]`); any other array is treated as
   a value, so a plain list (`'name' => ['a', 'b']`) becomes an `IN` condition. The
   operator is matched case-insensitively. A `['like', pattern]` entry (and the
-  other three LIKE operators) sends the pattern verbatim; a condition handed to
-  `OrConditionSpecification` directly is normalized the same way only in its
-  three-element `[operator, column, pattern]` form.
+  other three LIKE operators) sends the pattern verbatim. `['is', value]` and
+  `['is not', value]` are rendered as `=` / `!=`, exactly like the comparison
+  path: a `null` operand becomes `IS NULL` / `IS NOT NULL`, anything else a plain
+  equality — never a verbatim `IS 'value'`, which MySQL and PostgreSQL reject.
+  A condition handed to `OrConditionSpecification` directly is normalized the
+  same way only in its three-element `[operator, column, value]` form.
 
 ## License
 
diff --git a/README.ru.md b/README.ru.md
index e92b4c8..b6f2808 100644
--- a/README.ru.md
+++ b/README.ru.md
@@ -291,9 +291,12 @@ $spec = CompositeSpecification::create()
   другой массив трактуется как значение, поэтому простой список
   (`'name' => ['a', 'b']`) становится условием `IN`. Оператор сопоставляется
   case-insensitively. Запись `['like', pattern]` (и остальные три LIKE-оператора)
-  отправляет паттерн как есть; условие, переданное в `OrConditionSpecification`
-  напрямую, нормализуется так же только в трёхэлементной форме
-  `[operator, column, pattern]`.
+  отправляет паттерн как есть. `['is', value]` и `['is not', value]`
+  рендерятся как `=` / `!=` — так же, как на пути сравнения: операнд `null`
+  становится `IS NULL` / `IS NOT NULL`, любой другой — обычным равенством,
+  и никогда — буквальным `IS 'value'`, которое MySQL и PostgreSQL отвергают.
+  Условие, переданное в `OrConditionSpecification` напрямую, нормализуется так
+  же только в трёхэлементной форме `[operator, column, value]`.
 
 ## Лицензия
 
diff --git a/src/QueryBuildingVisitor.php b/src/QueryBuildingVisitor.php
index aaf5173..27680cd 100644
--- a/src/QueryBuildingVisitor.php
+++ b/src/QueryBuildingVisitor.php
@@ -162,7 +162,10 @@ public function visitOrCondition(OrConditionSpecification $specification): void
 
     /**
      * A LIKE written as `[operator, column, pattern]` carries the caller's
-     * wildcards in the pattern, so it is sent verbatim.
+     * wildcards in the pattern, so it is sent verbatim. `is` / `is not` are
+     * mapped to `=` / `!=` exactly as visitComparison() does: yiisoft/db
+     * renders `IS NULL` for a null operand, while a verbatim `IS 'value'` is a
+     * syntax error on MySQL and PostgreSQL (#34).
      *
      * @param array<array-key, mixed> $condition
      * @return array<array-key, mixed>
@@ -173,11 +176,14 @@ private function normalizeOrCondition(array $condition): array
             return $condition;
         }
         [$operator, $column, $value] = $condition;
-        if (!is_string(value: $operator) || !is_string(value: $column) || !is_string(value: $value)) {
+        if (!is_string(value: $operator) || !is_string(value: $column)) {
             return $condition;
         }
         $operator = mb_strtolower(string: $operator);
-        if (!in_array(needle: $operator, haystack: self::LIKE_OPERATORS, strict: true)) {
+        if ($operator === 'is' || $operator === 'is not') {
+            return [$operator === 'is' ? '=' : '!=', $column, $value];
+        }
+        if (!is_string(value: $value) || !in_array(needle: $operator, haystack: self::LIKE_OPERATORS, strict: true)) {
             return $condition;
         }
 
diff --git a/tests/Integration/SqliteIntegrationTest.php b/tests/Integration/SqliteIntegrationTest.php
index c25a575..bf7e4fd 100644
--- a/tests/Integration/SqliteIntegrationTest.php
+++ b/tests/Integration/SqliteIntegrationTest.php
@@ -325,6 +325,25 @@ public function likeInsideNotAndOr(): void
         Assert::same($this->ids($or), [5, 6, 7]);
     }
 
+    /**
+     * SQLite reads `IS 'pending'` as null-safe equality, so a verbatim `is`
+     * passes here while MySQL and PostgreSQL reject it (#34). The SQL is
+     * asserted, not only the rows: the rows would be the same either way.
+     */
+    public function orConditionIsRendersAsEquality(): void
+    {
+        $spec = CompositeSpecification::create()
+            ->withOrCondition(conditions: ['status' => ['is', 'pending'], 'name' => ['is not', null]]);
+
+        $query = (new Query($this->db))->from('items');
+        QueryApplier::apply(specification: $spec, query: $query);
+        $sql = $query->createCommand()->getRawSql();
+
+        Assert::string($sql)->contains('"status" = \'pending\'')->contains('"name" IS NOT NULL');
+        Assert::string($sql)->notContains(' IS \'');
+        Assert::same($this->ids($spec), [1, 2, 3, 4, 5]);
+    }
+
     public function orConditionLikeSendsThePatternVerbatim(): void
     {
         $this->db->createCommand()->insert('items', ['id' => 6, 'name' => 'Alpha%Beta', 'status' => 'active', 'price' => 60, 'created_at' => '2024-06-01'])->execute();
diff --git a/tests/QueryBuildingVisitorTest.php b/tests/QueryBuildingVisitorTest.php
index 409ceae..02dc462 100644
--- a/tests/QueryBuildingVisitorTest.php
+++ b/tests/QueryBuildingVisitorTest.php
@@ -189,6 +189,34 @@ public static function orConditionLikeProvider(): iterable
         ];
     }
 
+    /**
+     * @param array<array-key, mixed> $condition
+     * @param array<array-key, mixed> $expected
+     */
+    #[DataProvider('orConditionIsProvider')]
+    public function visitOrConditionMapsIsToEqualityLikeVisitComparison(array $condition, array $expected): void
+    {
+        $query = $this->makeQuery();
+        $visitor = new QueryBuildingVisitor(query: $query);
+        $spec = new OrConditionSpecification(conditions: [['status' => 'active'], $condition]);
+
+        $visitor->visitOrCondition(specification: $spec);
+
+        Assert::same($query->getWhere(), ['or', ['status' => 'active'], $expected]);
+    }
+
+    public static function orConditionIsProvider(): iterable
+    {
+        yield 'is null' => [['is', 'deleted_at', null], ['=', 'deleted_at', null]];
+        yield 'is not null' => [['is not', 'deleted_at', null], ['!=', 'deleted_at', null]];
+        yield 'IS in upper case' => [['IS', 'deleted_at', null], ['=', 'deleted_at', null]];
+        yield 'is with a string operand' => [['is', 'status', 'pending'], ['=', 'status', 'pending']];
+        yield 'is not with a string operand' => [['is not', 'status', 'pending'], ['!=', 'status', 'pending']];
+        yield 'is with a bool operand' => [['is', 'flag', true], ['=', 'flag', true]];
+        yield 'an is with a non-string column is untouched' => [['is', ['deleted_at'], null], ['is', ['deleted_at'], null]];
+        yield 'an is with two operands is untouched' => [['is', 'deleted_at'], ['is', 'deleted_at']];
+    }
+
     public function visitOrConditionEmpty(): void
     {
         $query = $this->makeQuery();