diff --git a/README.md b/README.md
index 720b372..7923fae 100644
--- a/README.md
+++ b/README.md
@@ -103,6 +103,9 @@ This version should be compatible with latest WordPress 5.6.
 
 ## Changelog ##
 
+### 1.6.1 / unreleased ###
+* Fix storage of user agent filter list (#28, props @BananaSquishee)
+
 ### 1.6.0 / 09.12.2020 ###
 
 Plugin renamed to _Statify Filter_.
diff --git a/inc/class-statifyblacklist-system.php b/inc/class-statifyblacklist-system.php
index 815de57..64a6fab 100644
--- a/inc/class-statifyblacklist-system.php
+++ b/inc/class-statifyblacklist-system.php
@@ -178,6 +178,30 @@ class StatifyBlacklist_System extends StatifyBlacklist {
 			self::update_options();
 		}
 
+		// Version older than 1.6.
+		if ( self::$options['version'] < 1.6 ) {
+			$options = self::$options;
+			if ( ! isset( $options['ua'] ) ) {
+				$options['ua'] = array(
+					'active'    => 0,
+					'regexp'    => 0,
+					'blacklist' => array(),
+				);
+			} elseif ( ! isset( $options['ua']['blacklist'] ) ) {
+				$options['ua']['blacklist'] = array();
+			} elseif ( isset( $options['ua'] ) ) {
+				// User agent strings got stored incorrectly in 1.6.0 - luckily the version was not updated, either.
+				$options['ua']['blacklist'] = array_flip( $options['ua']['blacklist'] );
+			}
+			$options['version'] = 1.6;
+			if ( self::$multisite ) {
+				update_site_option( 'statify-blacklist', $options );
+			} else {
+				update_option( 'statify-blacklist', $options );
+			}
+			self::update_options();
+		}
+
 		// Version older than current major release.
 		if ( self::VERSION_MAIN > self::$options['version'] ) {
 			// Merge default options with current config, assuming only additive changes.
diff --git a/inc/class-statifyblacklist.php b/inc/class-statifyblacklist.php
index 5c1d2f7..d059035 100644
--- a/inc/class-statifyblacklist.php
+++ b/inc/class-statifyblacklist.php
@@ -24,7 +24,7 @@ class StatifyBlacklist {
 	 * @since 1.4.0
 	 * @var int VERSION_MAIN
 	 */
-	const VERSION_MAIN = 1.4;
+	const VERSION_MAIN = 1.6;
 
 	/**
 	 * Operation mode "normal".
diff --git a/test/StatifyBlacklist_System_Test.php b/test/StatifyBlacklist_System_Test.php
index 9a13a5b..f94fe89 100644
--- a/test/StatifyBlacklist_System_Test.php
+++ b/test/StatifyBlacklist_System_Test.php
@@ -42,10 +42,12 @@ class StatifyBlacklist_System_Test extends PHPUnit\Framework\TestCase {
 		$options_updated = get_option( 'statify-blacklist' );
 
 		// Verify size against default options (no junk left).
-		$this->assertEquals( 4, count( $options_updated ) );
+		$this->assertEquals( 5, count( $options_updated ) );
 		$this->assertEquals( 4, count( $options_updated['referer'] ) );
 		$this->assertEquals( 4, count( $options_updated['target'] ) );
 		$this->assertEquals( 2, count( $options_updated['ip'] ) );
+		$this->assertEquals( 3, count( $options_updated['ua'] ) );
+		$this->assertEquals( 1.6, $options_updated['version'] );
 
 		// Verify that original attributes are unchanged.
 		$this->assertEquals( $options13['active_referer'], $options_updated['referer']['active'] );
@@ -60,8 +62,31 @@ class StatifyBlacklist_System_Test extends PHPUnit\Framework\TestCase {
 		$this->assertEquals( array(), $options_updated['target']['blacklist'] );
 		$this->assertEquals( 0, $options_updated['ip']['active'] );
 		$this->assertEquals( array(), $options_updated['ip']['blacklist'] );
+		$this->assertEquals( 0, $options_updated['ua']['active'] );
+		$this->assertEquals( 0, $options_updated['ua']['regexp'] );
+		$this->assertEquals( array(), $options_updated['ua']['blacklist'] );
 
 		// Verify that version number has changed to current release.
 		$this->assertEquals( StatifyBlacklist::VERSION_MAIN, $options_updated['version'] );
+
+		// Test upgrade of incorrectly stored user agent list in 1.6.
+		$options_updated['version']         = 1.4;
+		$options_updated['ua']['blacklist'] = array( 'user agent 1', 'user agent 2' );
+		update_option( 'statify-blacklist', $options_updated );
+
+		// Execute upgrade.
+		StatifyBlacklist_System::upgrade();
+
+		// Retrieve updated options.
+		$options_updated = get_option( 'statify-blacklist' );
+		$this->assertEquals(
+			array(
+				'user agent 1' => 0,
+				'user agent 2' => 1,
+			),
+			$options_updated['ua']['blacklist']
+		);
+		$this->assertEquals( 1.6, $options_updated['version'] );
+		$this->assertEquals( StatifyBlacklist::VERSION_MAIN, $options_updated['version'] );
 	}
 }
diff --git a/views/settings-page.php b/views/settings-page.php
index b7debe2..26407fb 100755
--- a/views/settings-page.php
+++ b/views/settings-page.php
@@ -88,7 +88,7 @@ if ( ! empty( $_POST['statifyblacklist'] ) ) {
 			);
 		}
 
-		// TODO: Extract user agent array.
+		// Extract user agent array.
 		if ( isset( $_POST['statifyblacklist']['ua']['blacklist'] ) ) {
 			$ua_string = sanitize_textarea_field( wp_unslash( $_POST['statifyblacklist']['ua']['blacklist'] ) );
 		}
@@ -139,7 +139,7 @@ if ( ! empty( $_POST['statifyblacklist'] ) ) {
 						? (int) $_POST['statifyblacklist']['ua']['active'] : 0,
 					'regexp'    => isset( $_POST['statifyblacklist']['ua']['regexp'] )
 						? (int) $_POST['statifyblacklist']['ua']['regexp'] : 0,
-					'blacklist' => $ua,
+					'blacklist' => array_flip( $ua ),
 				),
 				'version' => StatifyBlacklist::VERSION_MAIN,
 			)