diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index 28b65135a0..45922d6f65 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -3808,7 +3808,7 @@ function human_time_diff( $from, $to = 0 ) {
 function wp_trim_excerpt( $text = '', $post = null ) {
 	$raw_excerpt = $text;
 
-	if ( '' === $text ) {
+	if ( '' === trim( $text ) ) {
 		$post = get_post( $post );
 		$text = get_the_content( '', false, $post );
 
diff --git a/tests/phpunit/tests/formatting/WpTrimExcerpt.php b/tests/phpunit/tests/formatting/WpTrimExcerpt.php
index b2c026a957..01353c8e22 100644
--- a/tests/phpunit/tests/formatting/WpTrimExcerpt.php
+++ b/tests/phpunit/tests/formatting/WpTrimExcerpt.php
@@ -66,4 +66,19 @@ class Tests_Formatting_WpTrimExcerpt extends WP_UnitTestCase {
 			}
 		}
 	}
+
+	/**
+	 * @ticket 51042
+	 */
+	public function test_should_generate_excerpt_for_empty_values() {
+		$post = self::factory()->post->create(
+			array(
+				'post_content' => 'Post content',
+			)
+		);
+
+		$this->assertSame( 'Post content', wp_trim_excerpt( '', $post ) );
+		$this->assertSame( 'Post content', wp_trim_excerpt( null, $post ) );
+		$this->assertSame( 'Post content', wp_trim_excerpt( false, $post ) );
+	}
 }