diff --git a/src/ExchangeRateProvider/BaseCurrencyProvider.php b/src/ExchangeRateProvider/BaseCurrencyProvider.php
index 6051ffa..8f37fdb 100644
--- a/src/ExchangeRateProvider/BaseCurrencyProvider.php
+++ b/src/ExchangeRateProvider/BaseCurrencyProvider.php
@@ -4,6 +4,7 @@
 
 namespace Brick\Money\ExchangeRateProvider;
 
+use Brick\Math\BigNumber;
 use Brick\Money\ExchangeRateProvider;
 
 use Brick\Math\BigRational;
@@ -46,10 +47,10 @@ public function __construct(ExchangeRateProvider $provider, string $baseCurrency
     /**
      * {@inheritdoc}
      */
-    public function getExchangeRate(string $sourceCurrencyCode, string $targetCurrencyCode)
+    public function getExchangeRate(string $sourceCurrencyCode, string $targetCurrencyCode): BigNumber
     {
         if ($sourceCurrencyCode === $this->baseCurrencyCode) {
-            return $this->provider->getExchangeRate($sourceCurrencyCode, $targetCurrencyCode);
+            return BigNumber::of($this->provider->getExchangeRate($sourceCurrencyCode, $targetCurrencyCode));
         }
 
         if ($targetCurrencyCode === $this->baseCurrencyCode) {
diff --git a/tests/ExchangeRateProvider/BaseCurrencyProviderTest.php b/tests/ExchangeRateProvider/BaseCurrencyProviderTest.php
index 0b27167..c866311 100644
--- a/tests/ExchangeRateProvider/BaseCurrencyProviderTest.php
+++ b/tests/ExchangeRateProvider/BaseCurrencyProviderTest.php
@@ -4,6 +4,7 @@
 
 namespace Brick\Money\Tests\ExchangeRateProvider;
 
+use Brick\Math\BigNumber;
 use Brick\Money\ExchangeRateProvider;
 use Brick\Money\ExchangeRateProvider\BaseCurrencyProvider;
 use Brick\Money\ExchangeRateProvider\ConfigurableProvider;
@@ -38,7 +39,7 @@ private function getExchangeRateProvider() : ExchangeRateProvider
     public function testGetExchangeRate(string $sourceCurrencyCode, string $targetCurrencyCode, string $exchangeRate) : void
     {
         $rate = $this->getExchangeRateProvider()->getExchangeRate($sourceCurrencyCode, $targetCurrencyCode);
-        self::assertSame($exchangeRate, (string) BigRational::of($rate)->toScale(6, RoundingMode::DOWN));
+        self::assertSame($exchangeRate, (string) $rate->toScale(6, RoundingMode::DOWN));
     }
 
     public function providerGetExchangeRate() : array
@@ -60,4 +61,25 @@ public function providerGetExchangeRate() : array
             ['CAD', 'GBP', '0.727272'],
         ];
     }
+
+    /**
+     * @dataProvider providerReturnBigNumber
+     *
+     * @param BigNumber|float|int|string $rate
+     */
+    public function testReturnBigNumber($rate) : void
+    {
+        $configurableProvider = new ConfigurableProvider();
+        $configurableProvider->setExchangeRate('USD', 'EUR', $rate);
+        $baseProvider = new BaseCurrencyProvider($configurableProvider, 'USD');
+
+        $rate = $baseProvider->getExchangeRate('USD', 'EUR');
+
+        $this->assertInstanceOf(BigNumber::class, $rate);
+    }
+
+    public function providerReturnBigNumber() : array
+    {
+        return [[1], [1.1], ['1.0'], [BigNumber::of('1')]];
+    }
 }