diff --git a/wp-admin/custom-background.php b/wp-admin/custom-background.php
index 18dd786c70..f6869c952c 100644
--- a/wp-admin/custom-background.php
+++ b/wp-admin/custom-background.php
@@ -254,7 +254,7 @@ if ( get_background_image() ) {
 <?php endif; ?>
 <tr valign="top">
 <th scope="row"><?php _e('Select Image'); ?></th>
-<td><form enctype="multipart/form-data" id="upload-form" method="post" action="">
+<td><form enctype="multipart/form-data" id="upload-form" class="wp-upload-form" method="post" action="">
 	<p>
 		<label for="upload"><?php _e( 'Choose an image from your computer:' ); ?></label><br />
 		<input type="file" id="upload" name="import" />
diff --git a/wp-admin/custom-header.php b/wp-admin/custom-header.php
index d1055bd775..7a570e3403 100644
--- a/wp-admin/custom-header.php
+++ b/wp-admin/custom-header.php
@@ -525,7 +525,7 @@ class Custom_Image_Header {
 			printf( __( 'Suggested height is <strong>%1$d pixels</strong>.' ) . ' ', get_theme_support( 'custom-header', 'height' ) );
 	}
 	?></p>
-	<form enctype="multipart/form-data" id="upload-form" method="post" action="<?php echo esc_attr( add_query_arg( 'step', 2 ) ) ?>">
+	<form enctype="multipart/form-data" id="upload-form" class="wp-upload-form" method="post" action="<?php echo esc_attr( add_query_arg( 'step', 2 ) ) ?>">
 	<p>
 		<label for="upload"><?php _e( 'Choose an image from your computer:' ); ?></label><br />
 		<input type="file" id="upload" name="import" />
diff --git a/wp-admin/includes/plugin-install.php b/wp-admin/includes/plugin-install.php
index 452b4df02b..63a5f711f2 100644
--- a/wp-admin/includes/plugin-install.php
+++ b/wp-admin/includes/plugin-install.php
@@ -142,13 +142,13 @@ function install_search_form( $type_selector = true ) {
  */
 function install_plugins_upload( $page = 1 ) {
 ?>
-	<h4><?php _e('Install a plugin in .zip format') ?></h4>
-	<p class="install-help"><?php _e('If you have a plugin in a .zip format, you may install it by uploading it here.') ?></p>
-	<form method="post" enctype="multipart/form-data" action="<?php echo self_admin_url('update.php?action=upload-plugin') ?>">
-		<?php wp_nonce_field( 'plugin-upload') ?>
+	<h4><?php _e('Install a plugin in .zip format'); ?></h4>
+	<p class="install-help"><?php _e('If you have a plugin in a .zip format, you may install it by uploading it here.'); ?></p>
+	<form method="post" enctype="multipart/form-data" class="wp-upload-form" action="<?php echo self_admin_url('update.php?action=upload-plugin'); ?>">
+		<?php wp_nonce_field( 'plugin-upload'); ?>
 		<label class="screen-reader-text" for="pluginzip"><?php _e('Plugin zip file'); ?></label>
 		<input type="file" id="pluginzip" name="pluginzip" />
-		<input type="submit" class="button" value="<?php esc_attr_e('Install Now') ?>" />
+		<?php submit_button( __( 'Install Now' ), 'button', 'install-plugin-submit', false ); ?>
 	</form>
 <?php
 }
diff --git a/wp-admin/includes/template.php b/wp-admin/includes/template.php
index df073fa6a2..32962003c2 100644
--- a/wp-admin/includes/template.php
+++ b/wp-admin/includes/template.php
@@ -787,7 +787,7 @@ function wp_import_upload_form( $action ) {
 		<p><strong><?php echo $upload_dir['error']; ?></strong></p></div><?php
 	else :
 ?>
-<form enctype="multipart/form-data" id="import-upload-form" method="post" action="<?php echo esc_attr(wp_nonce_url($action, 'import-upload')); ?>">
+<form enctype="multipart/form-data" id="import-upload-form" method="post" class="wp-upload-form" action="<?php echo esc_attr(wp_nonce_url($action, 'import-upload')); ?>">
 <p>
 <label for="upload"><?php _e( 'Choose a file from your computer:' ); ?></label> (<?php printf( __('Maximum size: %s' ), $size ); ?>)
 <input type="file" id="upload" name="import" size="25" />
diff --git a/wp-admin/includes/theme-install.php b/wp-admin/includes/theme-install.php
index ff0ce01d92..5c135aa10a 100644
--- a/wp-admin/includes/theme-install.php
+++ b/wp-admin/includes/theme-install.php
@@ -134,10 +134,10 @@ add_action('install_themes_dashboard', 'install_themes_dashboard');
 
 function install_themes_upload($page = 1) {
 ?>
-<h4><?php _e('Install a theme in .zip format') ?></h4>
-<p class="install-help"><?php _e('If you have a theme in a .zip format, you may install it by uploading it here.') ?></p>
-<form method="post" enctype="multipart/form-data" action="<?php echo self_admin_url('update.php?action=upload-theme') ?>">
-	<?php wp_nonce_field( 'theme-upload') ?>
+<h4><?php _e('Install a theme in .zip format'); ?></h4>
+<p class="install-help"><?php _e('If you have a theme in a .zip format, you may install it by uploading it here.'); ?></p>
+<form method="post" enctype="multipart/form-data" class="wp-upload-form" action="<?php echo self_admin_url('update.php?action=upload-theme'); ?>">
+	<?php wp_nonce_field( 'theme-upload'); ?>
 	<input type="file" name="themezip" />
 	<?php submit_button( __( 'Install Now' ), 'button', 'install-theme-submit', false ); ?>
 </form>
diff --git a/wp-admin/js/common.js b/wp-admin/js/common.js
index a7b3c2d487..da9cb4f428 100644
--- a/wp-admin/js/common.js
+++ b/wp-admin/js/common.js
@@ -249,7 +249,7 @@ $(document).ready( function() {
 			sensitivity: 7,
 			interval: 90
 		});
-		
+
 		menu.on('focus.adminmenu', '.wp-submenu a', function(e){
 			$(e.target).closest('li.menu-top').addClass('opensub');
 		}).on('blur.adminmenu', '.wp-submenu a', function(e){
@@ -388,6 +388,20 @@ $(document).ready( function() {
 		if ( e.target.scrollIntoView )
 			e.target.scrollIntoView(false);
 	});
+
+	// Disable upload buttons until files are selected
+	(function(){
+		var button, input, form = $('form.wp-upload-form');
+		if ( ! form.length )
+			return;
+		button = form.find('input[type="submit"]');
+		input = form.find('input[type="file"]');
+		function toggleUploadButton() {
+			button.prop('disabled', '' === input.val());
+		}
+		toggleUploadButton();
+		input.on('change', toggleUploadButton);
+	})();
 });
 
 // internal use