diff --git a/lib/private/Security/Normalizer/IpAddress.php b/lib/private/Security/Normalizer/IpAddress.php
index b471c499440cb..9e7d84e7e3fee 100644
--- a/lib/private/Security/Normalizer/IpAddress.php
+++ b/lib/private/Security/Normalizer/IpAddress.php
@@ -92,7 +92,7 @@ private function getIPv6Subnet(string $ip, int $maskBits = 48): string {
 	}
 
 	/**
-	 * Gets either the /32 (IPv4) or the /128 (IPv6) subnet of an IP address
+	 * Gets either the /32 (IPv4) or the /64 (IPv6) subnet of an IP address
 	 *
 	 * @return string
 	 */
@@ -105,7 +105,7 @@ public function getSubnet(): string {
 		}
 		return $this->getIPv6Subnet(
 			$this->ip,
-			128
+			64
 		);
 	}
 
diff --git a/tests/lib/Security/Normalizer/IpAddressTest.php b/tests/lib/Security/Normalizer/IpAddressTest.php
index 16be71cb2253b..044fc52b4b9c1 100644
--- a/tests/lib/Security/Normalizer/IpAddressTest.php
+++ b/tests/lib/Security/Normalizer/IpAddressTest.php
@@ -37,11 +37,19 @@ public function subnetDataProvider() {
 			],
 			[
 				'2001:0db8:85a3:0000:0000:8a2e:0370:7334',
-				'2001:db8:85a3::8a2e:370:7334/128',
+				'2001:db8:85a3::/64',
+			],
+			[
+				'2001:db8:3333:4444:5555:6666:7777:8888',
+				'2001:db8:3333:4444::/64',
+			],
+			[
+				'::1234:5678',
+				'::/64',
 			],
 			[
 				'[::1]',
-				'::1/128',
+				'::/64',
 			],
 		];
 	}