diff --git a/OliverBooth/Data/Web/Configuration/SessionConfiguration.cs b/OliverBooth/Data/Web/Configuration/SessionConfiguration.cs
index 2b47a27..b41c566 100644
--- a/OliverBooth/Data/Web/Configuration/SessionConfiguration.cs
+++ b/OliverBooth/Data/Web/Configuration/SessionConfiguration.cs
@@ -17,6 +17,7 @@ internal sealed class SessionConfiguration : IEntityTypeConfiguration<Session>
         builder.Property(e => e.Updated).IsRequired();
         builder.Property(e => e.LastAccessed).IsRequired();
         builder.Property(e => e.Expires).IsRequired();
+        builder.Property(e => e.UserAgent).HasMaxLength(255).IsRequired();
         builder.Property(e => e.UserId);
         builder.Property(e => e.IpAddress).HasConversion<IPAddressToBytesConverter>().IsRequired();
         builder.Property(e => e.RequiresTotp).IsRequired();
diff --git a/OliverBooth/Data/Web/ISession.cs b/OliverBooth/Data/Web/ISession.cs
index 88f7b9c..d711057 100644
--- a/OliverBooth/Data/Web/ISession.cs
+++ b/OliverBooth/Data/Web/ISession.cs
@@ -49,9 +49,15 @@ public interface ISession
     /// <value>The update timestamp.</value>
     DateTimeOffset Updated { get; }
 
+    /// <summary>
+    ///     Gets the user agent string associated with this session.
+    /// </summary>
+    /// <value>The user agent string.</value>
+    string UserAgent { get; }
+
     /// <summary>
     ///     Gets the user ID associated with the session.
     /// </summary>
     /// <value>The user ID.</value>
     Guid UserId { get; }
-}
\ No newline at end of file
+}
diff --git a/OliverBooth/Data/Web/Session.cs b/OliverBooth/Data/Web/Session.cs
index 8d42b3c..b46624f 100644
--- a/OliverBooth/Data/Web/Session.cs
+++ b/OliverBooth/Data/Web/Session.cs
@@ -25,6 +25,9 @@ internal sealed class Session : ISession
     /// <inheritdoc />
     public DateTimeOffset Updated { get; set; }
 
+    /// <inheritdoc />
+    public string UserAgent { get; set; } = string.Empty;
+
     /// <inheritdoc />
     public Guid UserId { get; set; }
 }
diff --git a/OliverBooth/Services/SessionService.cs b/OliverBooth/Services/SessionService.cs
index 9ee415c..14908ed 100644
--- a/OliverBooth/Services/SessionService.cs
+++ b/OliverBooth/Services/SessionService.cs
@@ -55,7 +55,8 @@ internal sealed class SessionService : BackgroundService, ISessionService
             Updated = now,
             LastAccessed = now,
             Expires = now + TimeSpan.FromDays(1),
-            RequiresTotp = !string.IsNullOrWhiteSpace(user.Totp)
+            RequiresTotp = !string.IsNullOrWhiteSpace(user.Totp),
+            UserAgent = request.Headers.UserAgent.ToString()
         };
         EntityEntry<Session> entry = context.Sessions.Add(session);
         context.SaveChanges();
@@ -110,7 +111,7 @@ internal sealed class SessionService : BackgroundService, ISessionService
     public bool TryGetCurrentUser(HttpRequest request, HttpResponse response, [NotNullWhen(true)] out IUser? user)
     {
         user = null;
-        
+
         if (!TryGetSession(request, out ISession? session))
         {
             _logger.LogDebug("Session not found; redirecting");
@@ -203,16 +204,29 @@ internal sealed class SessionService : BackgroundService, ISessionService
         if (!remoteIpAddress.TryWriteBytes(remoteAddressBytes, out _) ||
             !session.IpAddress.TryWriteBytes(sessionAddressBytes, out _))
         {
+            _logger.LogWarning("Failed to write bytes for session {Id}", session.Id);
             return false;
         }
 
         if (!remoteAddressBytes.SequenceEqual(sessionAddressBytes))
         {
+            _logger.LogInformation("Session {Id} has IP mismatch (wanted {Expected}, got {Actual})", session.Id,
+                session.IpAddress, remoteIpAddress);
+            return false;
+        }
+
+        var userAgent = request.Headers.UserAgent.ToString();
+        if (session.UserAgent != userAgent)
+        {
+            _logger.LogInformation("Session {Id} has user agent mismatch (wanted {Expected}, got {Actual})", session.Id,
+                session.UserAgent, userAgent);
             return false;
         }
 
         if (!_userService.TryGetUser(session.UserId, out _))
         {
+            _logger.LogWarning("User {Id} not found for session {Session} (client {Ip})", session.UserId, session.Id,
+                remoteIpAddress);
             return false;
         }