diff --git a/src/wp-admin/includes/plugin.php b/src/wp-admin/includes/plugin.php
index c0ac17a881..bf2bc8a5ec 100644
--- a/src/wp-admin/includes/plugin.php
+++ b/src/wp-admin/includes/plugin.php
@@ -1329,6 +1329,21 @@ function add_menu_page( $page_title, $menu_title, $capability, $menu_slug, $func
 		$position            = $position + substr( base_convert( md5( $menu_slug . $menu_title ), 16, 10 ), -5 ) * 0.00001;
 		$menu[ "$position" ] = $new_menu;
 	} else {
+		if ( ! is_int( $position ) ) {
+			_doing_it_wrong(
+				__FUNCTION__,
+				sprintf(
+				/* translators: %s: add_submenu_page() */
+					__( 'The seventh parameter passed to %s should be an integer representing menu position.' ),
+					'<code>add_menu_page()</code>'
+				),
+				'6.0.0'
+			);
+			// If the position is not a string (i.e. float), convert it to string.
+			if ( ! is_string( $position ) ) {
+				$position = (string) $position;
+			}
+		}
 		$menu[ $position ] = $new_menu;
 	}
 
diff --git a/tests/phpunit/tests/admin/includesPlugin.php b/tests/phpunit/tests/admin/includesPlugin.php
index 2fde9195fd..52a4b509e9 100644
--- a/tests/phpunit/tests/admin/includesPlugin.php
+++ b/tests/phpunit/tests/admin/includesPlugin.php
@@ -296,11 +296,11 @@ class Tests_Admin_IncludesPlugin extends WP_UnitTestCase {
 	}
 
 	/**
-	 * Passing a string as position will fail.
+	 * Passing a string as position will fail in submenu.
 	 *
 	 * @ticket 48599
 	 */
-	public function test_passing_string_as_position_fires_doing_it_wrong() {
+	public function test_passing_string_as_position_fires_doing_it_wrong_submenu() {
 		$this->setExpectedIncorrectUsage( 'add_submenu_page' );
 		global $submenu, $menu;
 
@@ -324,6 +324,37 @@ class Tests_Admin_IncludesPlugin extends WP_UnitTestCase {
 		$this->assertSame( 'submenu_page_1', $submenu['main_slug'][1][2] );
 	}
 
+	/**
+	 * Passing a string as position will fail in menu.
+	 *
+	 * @ticket 48599
+	 */
+	public function test_passing_string_as_position_fires_doing_it_wrong_menu() {
+		$this->setExpectedIncorrectUsage( 'add_menu_page' );
+		global $submenu, $menu;
+
+		// Reset menus.
+		$submenu      = array();
+		$menu         = array();
+		$current_user = get_current_user_id();
+		$admin_user   = self::factory()->user->create( array( 'role' => 'administrator' ) );
+		wp_set_current_user( $admin_user );
+		set_current_screen( 'dashboard' );
+
+		// Setup a menu with some items.
+		add_menu_page( 'Main Menu', 'Main Menu', 'manage_options', 'main_slug', 'main_page_callback', 'icon_url', '1' );
+		add_menu_page( 'Main Menu 1', 'Main Menu 1', 'manage_options', 'main1_slug', 'main1_page_callback', 'icon_url1', 1.5 );
+
+		// Clean up the temporary user.
+		wp_set_current_user( $current_user );
+		wp_delete_user( $admin_user );
+
+		// Verify the menu was inserted.
+		$this->assertSame( 'main_slug', $menu[1][2] );
+		// Verify the menu was inserted correctly on passing float as position.
+		$this->assertSame( 'main1_slug', $menu['1.5'][2] );
+	}
+
 	public function test_is_plugin_active_true() {
 		activate_plugin( 'hello.php' );
 		$test = is_plugin_active( 'hello.php' );