diff --git a/lib/schema/bigint.js b/lib/schema/bigint.js
index 6baec1f7ef..4dcebcbd41 100644
--- a/lib/schema/bigint.js
+++ b/lib/schema/bigint.js
@@ -209,7 +209,7 @@ SchemaBigInt.prototype.castForQuery = function($conditional, val, context) {
       return handler.call(this, val);
     }
 
-    return this.applySetters(null, val, context);
+    return this.applySetters(val, context);
   }
 
   try {
diff --git a/lib/schema/boolean.js b/lib/schema/boolean.js
index a887a9e07e..1cbade08c6 100644
--- a/lib/schema/boolean.js
+++ b/lib/schema/boolean.js
@@ -253,7 +253,7 @@ SchemaBoolean.prototype.castForQuery = function($conditional, val, context) {
       return handler.call(this, val);
     }
 
-    return this.applySetters(null, val, context);
+    return this.applySetters(val, context);
   }
 
   try {
diff --git a/lib/schema/int32.js b/lib/schema/int32.js
index 51594934e9..6838d22f2b 100644
--- a/lib/schema/int32.js
+++ b/lib/schema/int32.js
@@ -7,6 +7,7 @@
 const CastError = require('../error/cast');
 const SchemaType = require('../schemaType');
 const castInt32 = require('../cast/int32');
+const handleBitwiseOperator = require('./operators/bitwise');
 
 /**
  * Int32 SchemaType constructor.
@@ -200,7 +201,11 @@ SchemaInt32.$conditionalHandlers = {
   $gt: handleSingle,
   $gte: handleSingle,
   $lt: handleSingle,
-  $lte: handleSingle
+  $lte: handleSingle,
+  $bitsAllClear: handleBitwiseOperator,
+  $bitsAnyClear: handleBitwiseOperator,
+  $bitsAllSet: handleBitwiseOperator,
+  $bitsAnySet: handleBitwiseOperator
 };
 
 /*!
@@ -228,7 +233,7 @@ SchemaInt32.prototype.castForQuery = function($conditional, val, context) {
       return handler.call(this, val);
     }
 
-    return this.applySetters(null, val, context);
+    return this.applySetters(val, context);
   }
 
   try {
diff --git a/test/cast.test.js b/test/cast.test.js
index 9ee9fbca1a..2be2186aae 100644
--- a/test/cast.test.js
+++ b/test/cast.test.js
@@ -123,6 +123,12 @@ describe('cast: ', function() {
         { x: { $bitsAnyClear: Buffer.from([3]) } });
     });
 
+    it('with int32 (gh-15170)', function() {
+      const schema = new Schema({ x: 'Int32' });
+      assert.deepEqual(cast(schema, { x: { $bitsAnySet: 3 } }),
+        { x: { $bitsAnySet: 3 } });
+    });
+
     it('throws when invalid', function() {
       const schema = new Schema({ x: Number });
       assert.throws(function() {
@@ -250,4 +256,10 @@ describe('cast: ', function() {
       'state.fieldFoo': '44'
     });
   });
+
+  it('treats unknown operators as passthrough (gh-15170)', function() {
+    const schema = new Schema({ x: Boolean });
+    assert.deepEqual(cast(schema, { x: { $someConditional: true } }),
+      { x: { $someConditional: true } });
+  });
 });