diff --git a/src/Rule/ForbidArithmeticOperationOnNonNumberRule.php b/src/Rule/ForbidArithmeticOperationOnNonNumberRule.php
index f95f947..493b873 100644
--- a/src/Rule/ForbidArithmeticOperationOnNonNumberRule.php
+++ b/src/Rule/ForbidArithmeticOperationOnNonNumberRule.php
@@ -18,6 +18,7 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Type\FloatType;
 use PHPStan\Type\IntegerType;
+use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
 use PHPStan\Type\UnionType;
 use PHPStan\Type\VerbosityLevel;
@@ -113,6 +114,12 @@ private function processBinary(
             return []; // array merge syntax
         }
 
+        if (($this->isBcMathNumber($leftType) && $this->isFloat($rightType))
+            || ($this->isFloat($leftType) && $this->isBcMathNumber($rightType))
+        ) {
+            return $this->buildBinaryErrors($operator, 'BcMath\\Number and float', $leftType, $rightType);
+        }
+
         if (
             $operator === '%' &&
             (!$leftType->isInteger()->yes() || !$rightType->isInteger()->yes())
@@ -136,7 +143,8 @@ private function isNumeric(Type $type): bool
         return $int->isSuperTypeOf($type)->yes()
             || $float->isSuperTypeOf($type)->yes()
             || $intOrFloat->isSuperTypeOf($type)->yes()
-            || ($this->allowNumericString && $type->isNumericString()->yes());
+            || ($this->allowNumericString && $type->isNumericString()->yes())
+            || $this->isBcMathNumber($type);
     }
 
     /**
@@ -164,4 +172,18 @@ private function buildBinaryErrors(
         return [$error];
     }
 
+    private function isBcMathNumber(Type $type): bool
+    {
+        $bcMathNumber = new ObjectType('BcMath\Number');
+
+        return $type->isSuperTypeOf($bcMathNumber)->yes();
+    }
+
+    private function isFloat(Type $type): bool
+    {
+        $float = new FloatType();
+
+        return $type->isSuperTypeOf($float)->yes();
+    }
+
 }
diff --git a/tests/Rule/ForbidArithmeticOperationOnNonNumberRuleTest.php b/tests/Rule/ForbidArithmeticOperationOnNonNumberRuleTest.php
index 458030e..a0b340c 100644
--- a/tests/Rule/ForbidArithmeticOperationOnNonNumberRuleTest.php
+++ b/tests/Rule/ForbidArithmeticOperationOnNonNumberRuleTest.php
@@ -5,6 +5,7 @@
 use LogicException;
 use PHPStan\Rules\Rule;
 use ShipMonk\PHPStan\RuleTestCase;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<ForbidArithmeticOperationOnNonNumberRule>
@@ -35,6 +36,26 @@ public function testNoNumericString(): void
         $this->analyseFile(__DIR__ . '/data/ForbidArithmeticOperationOnNonNumberRule/no-numeric-string.php');
     }
 
+    public function testBcMathNumber(): void
+    {
+        if (PHP_VERSION_ID < 80_400) {
+            self::markTestSkipped('Requires PHP 8.4');
+        }
+
+        $this->allowNumericString = true;
+        $this->analyseFile(__DIR__ . '/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number.php');
+    }
+
+    public function testBcMathNumberNoNumeric(): void
+    {
+        if (PHP_VERSION_ID < 80_400) {
+            self::markTestSkipped('Requires PHP 8.4');
+        }
+
+        $this->allowNumericString = false;
+        $this->analyseFile(__DIR__ . '/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number-no-numeric.php');
+    }
+
     protected function shouldFailOnPhpErrors(): bool
     {
         return false; // https://github.com/phpstan/phpstan-src/pull/3031
diff --git a/tests/Rule/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number-no-numeric.php b/tests/Rule/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number-no-numeric.php
new file mode 100644
index 0000000..7d198ef
--- /dev/null
+++ b/tests/Rule/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number-no-numeric.php
@@ -0,0 +1,38 @@
+<?php declare(strict_types = 1);
+
+namespace ShipMonk\PHPStan\Rule\data\ForbidArithmeticOperationOnNonNumberRule;
+use BcMath\Number;
+
+class BcMathNumberNoNumeric {
+
+    /**
+     * @param numeric-string $ns
+     */
+    public function testBcMathNumbers(Number $n, string $ns, int $int, float $float, int|float $intFloat): void {
+        +$n;
+        -$n;
+
+        $x = $n + $n;
+        $x = $n - $n;
+        $x = $n * $n;
+        $x = $n / $n;
+
+        $x = $n + $int;
+        $x = $int + $n;
+        $x = $n + $ns; // error: Using + over non-number (BcMath\Number + string)
+        $x = $ns + $n; // error: Using + over non-number (string + BcMath\Number)
+        $x = $n - $int;
+        $x = $int - $n;
+        $x = $n - $ns; // error: Using - over non-number (BcMath\Number - string)
+        $x = $ns - $n; // error: Using - over non-number (string - BcMath\Number)
+        $x = $n * $int;
+        $x = $int * $n;
+        $x = $n * $ns; // error: Using * over non-number (BcMath\Number * string)
+        $x = $ns * $n; // error: Using * over non-number (string * BcMath\Number)
+        $x = $n / $int;
+        $x = $int / $n;
+        $x = $n / $ns; // error: Using / over non-number (BcMath\Number / string)
+        $x = $ns / $n; // error: Using / over non-number (string / BcMath\Number)
+    }
+}
+
diff --git a/tests/Rule/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number.php b/tests/Rule/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number.php
new file mode 100644
index 0000000..4318b84
--- /dev/null
+++ b/tests/Rule/data/ForbidArithmeticOperationOnNonNumberRule/bcmath-number.php
@@ -0,0 +1,54 @@
+<?php declare(strict_types = 1);
+
+namespace ForbidArithmeticOperationOnNonNumberRule;
+use BcMath\Number;
+
+class BcMathNumber {
+
+    /**
+     * @param numeric-string $ns
+     */
+    public function testBcMathNumbers(Number $n, string $ns, int $int, float $float, int|float $intFloat): void {
+        +$n;
+        -$n;
+
+        $x = $n + $n;
+        $x = $n - $n;
+        $x = $n * $n;
+        $x = $n / $n;
+
+        $x = $n + $int;
+        $x = $int + $n;
+        $x = $n + $ns;
+        $x = $ns + $n;
+        $x = $n - $int;
+        $x = $int - $n;
+        $x = $n - $ns;
+        $x = $ns - $n;
+        $x = $n * $int;
+        $x = $int * $n;
+        $x = $n * $ns;
+        $x = $ns * $n;
+        $x = $n / $int;
+        $x = $int / $n;
+        $x = $n / $ns;
+        $x = $ns / $n;
+
+        $x = $n + $float; // error: Using + over BcMath\Number and float (BcMath\Number + float)
+        $x = $float + $n; // error: Using + over BcMath\Number and float (float + BcMath\Number)
+        $x = $n - $float; // error: Using - over BcMath\Number and float (BcMath\Number - float)
+        $x = $float - $n; // error: Using - over BcMath\Number and float (float - BcMath\Number)
+        $x = $n * $float; // error: Using * over BcMath\Number and float (BcMath\Number * float)
+        $x = $float * $n; // error: Using * over BcMath\Number and float (float * BcMath\Number)
+        $x = $n / $float; // error: Using / over BcMath\Number and float (BcMath\Number / float)
+        $x = $float / $n; // error: Using / over BcMath\Number and float (float / BcMath\Number)
+        $x = $n % $float; // error: Using % over BcMath\Number and float (BcMath\Number % float)
+        $x = $float % $n; // error: Using % over BcMath\Number and float (float % BcMath\Number)
+        $x = $n ** $float; // error: Using ** over BcMath\Number and float (BcMath\Number ** float)
+        $x = $float ** $n; // error: Using ** over BcMath\Number and float (float ** BcMath\Number)
+
+        $x = $n + $intFloat; // error: Using + over BcMath\Number and float (BcMath\Number + float|int)
+        $x = $intFloat + $n; // error: Using + over BcMath\Number and float (float|int + BcMath\Number)
+    }
+}
+