diff --git a/sites/+instructions/Chinese.txt b/sites/+instructions/Chinese [zh].txt
similarity index 100%
rename from sites/+instructions/Chinese.txt
rename to sites/+instructions/Chinese [zh].txt
diff --git a/sites/+instructions/Czech.txt b/sites/+instructions/Czech [cs].txt
similarity index 100%
rename from sites/+instructions/Czech.txt
rename to sites/+instructions/Czech [cs].txt
diff --git a/sites/+instructions/English.txt b/sites/+instructions/English [en].txt
similarity index 100%
rename from sites/+instructions/English.txt
rename to sites/+instructions/English [en].txt
diff --git a/sites/+instructions/Esperanto.txt b/sites/+instructions/Esperanto [eo].txt
similarity index 100%
rename from sites/+instructions/Esperanto.txt
rename to sites/+instructions/Esperanto [eo].txt
diff --git a/sites/+instructions/Finnish.txt b/sites/+instructions/Finnish [fi].txt
similarity index 100%
rename from sites/+instructions/Finnish.txt
rename to sites/+instructions/Finnish [fi].txt
diff --git a/sites/+instructions/Russian.txt b/sites/+instructions/Russian [ru].txt
similarity index 100%
rename from sites/+instructions/Russian.txt
rename to sites/+instructions/Russian [ru].txt
diff --git a/sites/instructions/index.php b/sites/instructions/index.php
index 36e3223..978b229 100644
--- a/sites/instructions/index.php
+++ b/sites/instructions/index.php
@@ -2,7 +2,15 @@
 	require_once '+getenv.php';
 
 	$instruction_files = glob("+instructions/*.txt");
-	function file_language($file) { return pathinfo($file)['filename']; }
+	function file_language($file) {
+		$filename = pathinfo($file)['filename'];
+		return explode(" ", $filename)[0];
+	}
+	function file_language_code($file) {
+		$filename = pathinfo($file)['filename'];
+		$code_in_brackets = explode(" ", $filename)[1];
+		return mb_substr($code_in_brackets, 1, mb_strlen($code_in_brackets) - 2);
+	}
 
 	$languages = array_map('file_language', array_slice($instruction_files, 0, 10));
 	$language_enumeration = join(", ", $languages);
@@ -56,15 +64,13 @@
 				type="radio"
 				<?=file_language($file) == 'English' ? 'checked="checked"' : ''?>
 			><label for="language-selection-<?=$i?>">&nbsp;<?=
-					// Name of the language
-					// Can be later parsed from i.e. first line of file
 					file_language($file);
 			?></label>
 <?php endforeach; ?>
 
 			<article id="instructions">
 <?php foreach ($instruction_files as $i => $file): ?>
-			<section id="instructions-<?=$i?>" class="instructions"><?php
+			<section id="instructions-<?=$i?>" class="instructions" lang="<?=file_language_code($file)?>"><?php
 				// Sanitization as second layer of protection
 				// for user-submitted instruction files.
 				// Should not ever have to be used.