diff --git a/src/wp-admin/edit-comments.php b/src/wp-admin/edit-comments.php
index fc105feb36..f5448ab349 100644
--- a/src/wp-admin/edit-comments.php
+++ b/src/wp-admin/edit-comments.php
@@ -191,7 +191,7 @@ if ( $post_id ) {
 	_e( 'Comments' );
 }
 
-if ( isset($_REQUEST['s']) && $_REQUEST['s'] ) {
+if ( isset($_REQUEST['s']) && strlen( $_REQUEST['s'] ) ) {
 	echo '<span class="subtitle">';
 	/* translators: %s: search keywords */
 	printf( __( 'Search results for &#8220;%s&#8221;' ),
diff --git a/src/wp-admin/edit-tags.php b/src/wp-admin/edit-tags.php
index 846928caa8..713c8b9472 100644
--- a/src/wp-admin/edit-tags.php
+++ b/src/wp-admin/edit-tags.php
@@ -311,8 +311,11 @@ if ( is_plugin_active( 'wpcat2tag-importer/wpcat2tag-importer.php' ) ) {
 
 <div class="wrap nosubsub">
 <h1><?php echo esc_html( $title );
-if ( !empty($_REQUEST['s']) )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( wp_unslash($_REQUEST['s']) ) ); ?>
+if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
+	/* translators: %s: search keywords */
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( wp_unslash( $_REQUEST['s'] ) ) );
+}
+?>
 </h1>
 
 <?php if ( $message ) : ?>
diff --git a/src/wp-admin/edit.php b/src/wp-admin/edit.php
index 62c70e2bc3..27d8f6895b 100644
--- a/src/wp-admin/edit.php
+++ b/src/wp-admin/edit.php
@@ -303,8 +303,11 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 echo esc_html( $post_type_object->labels->name );
 if ( current_user_can( $post_type_object->cap->create_posts ) )
 	echo ' <a href="' . esc_url( admin_url( $post_new_file ) ) . '" class="page-title-action">' . esc_html( $post_type_object->labels->add_new ) . '</a>';
-if ( ! empty( $_REQUEST['s'] ) )
-	printf( ' <span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', get_search_query() );
+
+if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
+	/* translators: %s: search keywords */
+	printf( ' <span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', get_search_query() );
+}
 ?></h1>
 
 <?php
diff --git a/src/wp-admin/includes/class-wp-plugins-list-table.php b/src/wp-admin/includes/class-wp-plugins-list-table.php
index 5194f5210f..9fb81030ef 100644
--- a/src/wp-admin/includes/class-wp-plugins-list-table.php
+++ b/src/wp-admin/includes/class-wp-plugins-list-table.php
@@ -75,7 +75,7 @@ class WP_Plugins_List_Table extends WP_List_Table {
 	public function prepare_items() {
 		global $status, $plugins, $totals, $page, $orderby, $order, $s;
 
-		wp_reset_vars( array( 'orderby', 'order', 's' ) );
+		wp_reset_vars( array( 'orderby', 'order' ) );
 
 		/**
 		 * Filter the full array of plugins to list in the Plugins list table.
@@ -224,7 +224,7 @@ class WP_Plugins_List_Table extends WP_List_Table {
 			}
 		}
 
-		if ( $s ) {
+		if ( strlen( $s ) ) {
 			$status = 'search';
 			$plugins['search'] = array_filter( $plugins['all'], array( $this, '_search_callback' ) );
 		}
@@ -268,17 +268,16 @@ class WP_Plugins_List_Table extends WP_List_Table {
 	}
 
 	/**
-	 * @staticvar string $term
+	 * @global string $s
+	 *
 	 * @param array $plugin
 	 * @return bool
 	 */
 	public function _search_callback( $plugin ) {
-		static $term = null;
-		if ( is_null( $term ) )
-			$term = wp_unslash( $_REQUEST['s'] );
+		global $s;
 
 		foreach ( $plugin as $value ) {
-			if ( is_string( $value ) && false !== stripos( strip_tags( $value ), $term ) ) {
+			if ( is_string( $value ) && false !== stripos( strip_tags( $value ), $s ) ) {
 				return true;
 			}
 		}
diff --git a/src/wp-admin/link-manager.php b/src/wp-admin/link-manager.php
index 5cf80cdf2c..4dc3015179 100644
--- a/src/wp-admin/link-manager.php
+++ b/src/wp-admin/link-manager.php
@@ -74,8 +74,11 @@ if ( ! current_user_can('manage_links') )
 
 <div class="wrap nosubsub">
 <h1><?php echo esc_html( $title ); ?> <a href="link-add.php" class="page-title-action"><?php echo esc_html_x('Add New', 'link'); ?></a> <?php
-if ( !empty($_REQUEST['s']) )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( wp_unslash($_REQUEST['s']) ) ); ?>
+if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
+	/* translators: %s: search keywords */
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( wp_unslash( $_REQUEST['s'] ) ) );
+}
+?>
 </h1>
 
 <?php
diff --git a/src/wp-admin/network/sites.php b/src/wp-admin/network/sites.php
index a0b699f174..a87dfd2b21 100644
--- a/src/wp-admin/network/sites.php
+++ b/src/wp-admin/network/sites.php
@@ -288,7 +288,9 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 	<a href="<?php echo network_admin_url('site-new.php'); ?>" class="page-title-action"><?php echo esc_html_x( 'Add New', 'site' ); ?></a>
 <?php endif; ?>
 
-<?php if ( isset( $_REQUEST['s'] ) && $_REQUEST['s'] ) {
+<?php
+if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
+	/* translators: %s: search keywords */
 	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $s ) );
 } ?>
 </h1>
diff --git a/src/wp-admin/network/themes.php b/src/wp-admin/network/themes.php
index af22af1efe..29dd9e5b57 100644
--- a/src/wp-admin/network/themes.php
+++ b/src/wp-admin/network/themes.php
@@ -239,8 +239,11 @@ require_once(ABSPATH . 'wp-admin/admin-header.php');
 
 <div class="wrap">
 <h1><?php echo esc_html( $title ); if ( current_user_can('install_themes') ) { ?> <a href="theme-install.php" class="page-title-action"><?php echo esc_html_x('Add New', 'theme'); ?></a><?php }
-if ( $s )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( $s ) ); ?>
+if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
+	/* translators: %s: search keywords */
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $s ) );
+}
+?>
 </h1>
 
 <?php
diff --git a/src/wp-admin/network/users.php b/src/wp-admin/network/users.php
index f55ea6ccab..4e56ca3339 100644
--- a/src/wp-admin/network/users.php
+++ b/src/wp-admin/network/users.php
@@ -212,8 +212,10 @@ if ( isset( $_REQUEST['updated'] ) && $_REQUEST['updated'] == 'true' && ! empty(
 		<a href="<?php echo network_admin_url('user-new.php'); ?>" class="page-title-action"><?php echo esc_html_x( 'Add New', 'user' ); ?></a><?php
 	endif;
 
-	if ( !empty( $usersearch ) )
-	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $usersearch ) );
+	if ( strlen( $usersearch ) ) {
+		/* translators: %s: search keywords */
+		printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $usersearch ) );
+	}
 	?>
 	</h1>
 
diff --git a/src/wp-admin/plugins.php b/src/wp-admin/plugins.php
index 176f294e47..a55001e253 100644
--- a/src/wp-admin/plugins.php
+++ b/src/wp-admin/plugins.php
@@ -481,9 +481,14 @@ if ( ! empty( $invalid ) ) {
 <h1><?php echo esc_html( $title );
 if ( ( ! is_multisite() || is_network_admin() ) && current_user_can('install_plugins') ) { ?>
  <a href="<?php echo self_admin_url( 'plugin-install.php' ); ?>" class="page-title-action"><?php echo esc_html_x('Add New', 'plugin'); ?></a>
-<?php }
-if ( $s )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( $s ) ); ?>
+<?php
+}
+
+if ( strlen( $s ) ) {
+	/* translators: %s: search keywords */
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $s ) );
+}
+?>
 </h1>
 
 <?php
diff --git a/src/wp-admin/upload.php b/src/wp-admin/upload.php
index 65bb790dae..6e089ac86f 100644
--- a/src/wp-admin/upload.php
+++ b/src/wp-admin/upload.php
@@ -220,8 +220,11 @@ echo esc_html( $title );
 if ( current_user_can( 'upload_files' ) ) { ?>
 	<a href="media-new.php" class="page-title-action"><?php echo esc_html_x('Add New', 'file'); ?></a><?php
 }
-if ( ! empty( $_REQUEST['s'] ) )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', get_search_query() ); ?>
+if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
+	/* translators: %s: search keywords */
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', get_search_query() );
+}
+?>
 </h1>
 
 <?php
diff --git a/src/wp-admin/users.php b/src/wp-admin/users.php
index e02c3943e8..8bd8c6dd66 100644
--- a/src/wp-admin/users.php
+++ b/src/wp-admin/users.php
@@ -481,8 +481,11 @@ if ( current_user_can( 'create_users' ) ) { ?>
 	<a href="user-new.php" class="page-title-action"><?php echo esc_html_x( 'Add Existing', 'user' ); ?></a>
 <?php }
 
-if ( $usersearch )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( $usersearch ) ); ?>
+if ( strlen( $usersearch ) ) {
+	/* translators: %s: search keywords */
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $usersearch ) );
+}
+?>
 </h1>
 
 <?php $wp_list_table->views(); ?>