diff --git a/lib/class-wp-theme-json-gutenberg.php b/lib/class-wp-theme-json-gutenberg.php
index b2b3fa997b8cd..8c2857fa89d0c 100644
--- a/lib/class-wp-theme-json-gutenberg.php
+++ b/lib/class-wp-theme-json-gutenberg.php
@@ -3389,7 +3389,7 @@ public function set_spacing_sizes() {
 			|| ! is_numeric( $spacing_scale['mediumStep'] )
 			|| ( '+' !== $spacing_scale['operator'] && '*' !== $spacing_scale['operator'] ) ) {
 			if ( ! empty( $spacing_scale ) ) {
-				_doing_it_wrong( __METHOD__, __( 'Some of the theme.json settings.spacing.spacingScale values are invalid', 'gutenberg' ), '6.1.0' );
+				trigger_error( __( 'Some of the theme.json settings.spacing.spacingScale values are invalid', 'gutenberg' ), E_USER_NOTICE );
 			}
 			return null;
 		}
diff --git a/phpunit/class-wp-theme-json-test.php b/phpunit/class-wp-theme-json-test.php
index 35747a290ca74..6ccbe2fb1d03b 100644
--- a/phpunit/class-wp-theme-json-test.php
+++ b/phpunit/class-wp-theme-json-test.php
@@ -1282,7 +1282,8 @@ public function data_generate_spacing_scale_fixtures() {
 	 * @dataProvider data_set_spacing_sizes_when_invalid
 	 */
 	public function test_set_spacing_sizes_when_invalid( $spacing_scale, $expected_output ) {
-		$this->setExpectedIncorrectUsage( 'WP_Theme_JSON_Gutenberg::set_spacing_sizes' );
+		$this->expectException( Exception::class );
+		$this->expectExceptionMessage( 'Some of the theme.json settings.spacing.spacingScale values are invalid' );
 
 		$theme_json = new WP_Theme_JSON_Gutenberg(
 			array(
@@ -1295,6 +1296,15 @@ public function test_set_spacing_sizes_when_invalid( $spacing_scale, $expected_o
 			)
 		);
 
+		// Ensure PHPUnit 10 compatibility.
+		set_error_handler(
+			static function ( $errno, $errstr ) {
+				restore_error_handler();
+				throw new Exception( $errstr, $errno );
+			},
+			E_ALL
+		);
+
 		$theme_json->set_spacing_sizes();
 		$this->assertSame( $expected_output, _wp_array_get( $theme_json->get_raw_data(), array( 'settings', 'spacing', 'spacingSizes', 'default' ) ) );
 	}