diff --git a/modules/ppcp-api-client/src/Repository/class-applicationcontextrepository.php b/modules/ppcp-api-client/src/Repository/class-applicationcontextrepository.php
index a50d934b5..bfc28b25a 100644
--- a/modules/ppcp-api-client/src/Repository/class-applicationcontextrepository.php
+++ b/modules/ppcp-api-client/src/Repository/class-applicationcontextrepository.php
@@ -67,12 +67,16 @@ class ApplicationContextRepository {
 	 */
 	protected function valid_bcp47_code() {
 		$locale = str_replace( '_', '-', get_user_locale() );
-		$parts  = explode( '-', $locale );
 
-		if ( count( $parts ) < 3 ) {
+		if ( preg_match( '/^[a-z]{2}(?:-[A-Z][a-z]{3})?(?:-(?:[A-Z]{2}))?$/', $locale ) ) {
 			return $locale;
 		}
 
-		return substr( $locale, 0, strrpos( $locale, '-' ) );
+		$parts = explode( '-', $locale );
+		if ( count( $parts ) === 3 ) {
+			return substr( $locale, 0, strrpos( $locale, '-' ) );
+		}
+
+		return 'en';
 	}
 }
diff --git a/modules/ppcp-button/src/Assets/class-smartbutton.php b/modules/ppcp-button/src/Assets/class-smartbutton.php
index 508150c29..c1dfa38c9 100644
--- a/modules/ppcp-button/src/Assets/class-smartbutton.php
+++ b/modules/ppcp-button/src/Assets/class-smartbutton.php
@@ -726,7 +726,6 @@ class SmartButton implements SmartButtonInterface {
 		$params = array(
 			'client-id'        => $this->client_id,
 			'currency'         => get_woocommerce_currency(),
-			'locale'           => $this->valid_locale_code(),
 			'integration-date' => PAYPAL_INTEGRATION_DATE,
 			'components'       => implode( ',', $this->components() ),
 			'vault'            => $this->can_save_vault_token() ?
@@ -957,20 +956,4 @@ class SmartButton implements SmartButtonInterface {
 		}
 		return false;
 	}
-
-	/**
-	 * Returns a PayPal-supported locale code, for example de_DE_formal becomes de_DE.
-	 *
-	 * @return string
-	 */
-	protected function valid_locale_code(): string {
-		$locale = get_user_locale();
-		$parts  = explode( '_', $locale );
-
-		if ( count( $parts ) < 3 ) {
-			return $locale;
-		}
-
-		return substr( $locale, 0, strrpos( $locale, '_' ) );
-	}
 }
diff --git a/tests/PHPUnit/ApiClient/Repository/ApplicationContextRepositoryTest.php b/tests/PHPUnit/ApiClient/Repository/ApplicationContextRepositoryTest.php
index 00d892142..477efc585 100644
--- a/tests/PHPUnit/ApiClient/Repository/ApplicationContextRepositoryTest.php
+++ b/tests/PHPUnit/ApiClient/Repository/ApplicationContextRepositoryTest.php
@@ -31,6 +31,8 @@ class ApplicationContextRepositoryTest extends TestCase
         return [
             'de-DE' => ['de-DE', 'de-DE'],
             'de-DE-formal' => ['de-DE-formal', 'de-DE'],
+            'de' => ['de', 'de'],
+            'ceb' => ['ceb', 'en'],
         ];
     }
 }
diff --git a/tests/PHPUnit/Button/Assets/SmartButtonTest.php b/tests/PHPUnit/Button/Assets/SmartButtonTest.php
deleted file mode 100644
index 264b73886..000000000
--- a/tests/PHPUnit/Button/Assets/SmartButtonTest.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php
-declare(strict_types=1);
-
-namespace WooCommerce\PayPalCommerce\Button\Assets;
-
-use WooCommerce\PayPalCommerce\TestCase;
-use function Brain\Monkey\Functions\when;
-
-class SmartButtonTest extends TestCase
-{
-    /**
-     * @dataProvider provider
-     */
-    public function test_valid_locale_code($input, $output)
-    {
-        $testee = $this->getMockBuilder(SmartButton::class)
-            ->disableOriginalConstructor()
-            ->getMock();
-
-        $method = new \ReflectionMethod($testee, 'valid_locale_code');
-        $method->setAccessible(true);
-
-        when('get_user_locale')->justReturn($input);
-
-        $this->assertSame($output, $method->invoke($testee));
-    }
-
-    public function provider()
-    {
-        return [
-            'de_DE' => ['de_DE', 'de_DE'],
-            'de_DE_formal' => ['de_DE_formal', 'de_DE'],
-        ];
-    }
-}