diff --git a/PluralKit.Bot/Commands/MemberCommands.cs b/PluralKit.Bot/Commands/MemberCommands.cs
index 9933492e..9187df69 100644
--- a/PluralKit.Bot/Commands/MemberCommands.cs
+++ b/PluralKit.Bot/Commands/MemberCommands.cs
@@ -1,4 +1,3 @@
-using System.Collections.Generic;
 using System.Linq;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
@@ -164,6 +163,20 @@ namespace PluralKit.Bot.Commands
                 return new ProxyTag(prefixAndSuffix[0], prefixAndSuffix[1]);
             }
             
+            async Task<bool> WarnOnConflict(ProxyTag newTag)
+            {
+                var conflicts = (await _data.GetConflictingProxies(ctx.System, newTag))
+                    .Where(m => m.Id != target.Id)
+                    .ToList();
+
+                if (conflicts.Count <= 0) return true;
+
+                var conflictList = conflicts.Select(m => $"- **{m.Name}**");
+                var msg = await ctx.Reply(
+                    $"{Emojis.Warn} The following members have conflicting proxy tags:\n{string.Join('\n', conflictList)}\nDo you want to proceed anyway?");
+                return await ctx.PromptYesNo(msg);
+            }
+            
             // "Sub"command: no arguments clearing
             if (!ctx.HasNext())
             {
@@ -175,7 +188,7 @@ namespace PluralKit.Bot.Commands
                     if (!await ctx.PromptYesNo(msg))
                         throw Errors.GenericCancelled();
                 }
-
+                
                 target.ProxyTags = new ProxyTag[] { };
                 
                 await _data.SaveMember(target);
@@ -190,6 +203,9 @@ namespace PluralKit.Bot.Commands
                 if (target.ProxyTags.Contains(tagToAdd))
                     throw Errors.ProxyTagAlreadyExists(tagToAdd, target);
                 
+                if (!await WarnOnConflict(tagToAdd))
+                    throw Errors.GenericCancelled();
+
                 // It's not guaranteed the list's mutable, so we force it to be
                 target.ProxyTags = target.ProxyTags.ToList();
                 target.ProxyTags.Add(tagToAdd);
@@ -224,6 +240,9 @@ namespace PluralKit.Bot.Commands
                 // already more than one proxy tag.
                 if (target.ProxyTags.Count > 1)
                     throw Errors.LegacyAlreadyHasProxyTag(requestedTag, target);
+                
+                if (!await WarnOnConflict(requestedTag))
+                    throw Errors.GenericCancelled();
 
                 target.ProxyTags = new[] {requestedTag};
                 
diff --git a/PluralKit.Core/Stores.cs b/PluralKit.Core/Stores.cs
index 3a9c93d3..5015ee54 100644
--- a/PluralKit.Core/Stores.cs
+++ b/PluralKit.Core/Stores.cs
@@ -1,11 +1,9 @@
-using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
-using App.Metrics.Logging;
+
 using Dapper;
 using NodaTime;
-using Npgsql;
 
 using Serilog;
 
@@ -109,7 +107,17 @@ namespace PluralKit {
         /// Gets the member count of a system.
         /// </summary>
         Task<int> GetSystemMemberCount(PKSystem system);
-        
+
+        /// <summary>
+        /// Gets a list of members with proxy tags that conflict with the given tags.
+        ///
+        /// A set of proxy tags A conflict with proxy tags B if both A's prefix and suffix
+        /// are a "subset" of B's. In other words, if A's prefix *starts* with B's prefix
+        /// and A's suffix *ends* with B's suffix, the tag pairs are considered conflicting.
+        /// </summary>
+        /// <param name="system">The system to check in.</param>
+        Task<IEnumerable<PKMember>> GetConflictingProxies(PKSystem system, ProxyTag tag);
+
         /// <summary>
         /// Creates a system, auto-generating its corresponding IDs.
         /// </summary>
@@ -359,6 +367,23 @@ namespace PluralKit {
             _logger = logger;
         }
 
+        public async Task<IEnumerable<PKMember>> GetConflictingProxies(PKSystem system, ProxyTag tag)
+        {
+            using (var conn = await _conn.Obtain())
+                // return await conn.QueryAsync<PKMember>("select * from (select *, (unnest(proxy_tags)).prefix as prefix, (unnest(proxy_tags)).suffix as suffix from members where system = @System) as _ where prefix ilike @Prefix and suffix ilike @Suffix", new
+                // {
+                //     System = system.Id,
+                //     Prefix = tag.Prefix.Replace("%", "\\%") + "%",
+                //     Suffix = "%" + tag.Suffix.Replace("%", "\\%")
+                // });
+                return await conn.QueryAsync<PKMember>("select * from (select *, (unnest(proxy_tags)).prefix as prefix, (unnest(proxy_tags)).suffix as suffix from members where system = @System) as _ where prefix = @Prefix and suffix = @Suffix", new
+                {
+                    System = system.Id,
+                    Prefix = tag.Prefix,
+                    Suffix = tag.Suffix
+                });
+        }
+
         public async Task<PKSystem> CreateSystem(string systemName = null) {
             string hid;
             do