diff --git a/app/models/ip_ban.rb b/app/models/ip_ban.rb
index 4091014c4..c2daec5b8 100644
--- a/app/models/ip_ban.rb
+++ b/app/models/ip_ban.rb
@@ -69,8 +69,8 @@ class IpBan < ApplicationRecord
       errors.add(:ip_addr, "may not have a subnet bigger than /24")
     elsif partial_ban? && ip_addr.ipv4? && ip_addr.prefix < 8
       errors.add(:ip_addr, "may not have a subnet bigger than /8")
-    elsif full_ban? && ip_addr.ipv6? && ip_addr.prefix < 64
-      errors.add(:ip_addr, "may not have a subnet bigger than /64")
+    elsif full_ban? && ip_addr.ipv6? && ip_addr.prefix < 48
+      errors.add(:ip_addr, "may not have a subnet bigger than /48")
     elsif partial_ban? && ip_addr.ipv6? && ip_addr.prefix < 20
       errors.add(:ip_addr, "may not have a subnet bigger than /20")
     elsif new_record? && IpBan.active.where(category: category).ip_matches(subnetted_ip).exists?
diff --git a/test/unit/ip_ban_test.rb b/test/unit/ip_ban_test.rb
index fd2e408c5..af211ce83 100644
--- a/test/unit/ip_ban_test.rb
+++ b/test/unit/ip_ban_test.rb
@@ -31,6 +31,7 @@ class IpBanTest < ActiveSupport::TestCase
     should allow_value("1.2.3.4/24").for(:ip_addr)
     should allow_value("ABCD::1234").for(:ip_addr)
     should allow_value("ABCD::1234/64").for(:ip_addr)
+    should allow_value("ABCD::1234/48").for(:ip_addr)
 
     should_not allow_value("").for(:ip_addr)
     should_not allow_value("foo").for(:ip_addr)
@@ -39,5 +40,6 @@ class IpBanTest < ActiveSupport::TestCase
     should_not allow_value("127.0.0.1").for(:ip_addr)
     should_not allow_value("1.2.3.4/16").for(:ip_addr)
     should_not allow_value("ABCD::1234/32").for(:ip_addr)
+    should_not allow_value("ABCD::1234/47").for(:ip_addr)
   end
 end